Changjiang

THE CHANGJIANG cuts through the heart of CHINA and is regarded by the Chinese as the geographical marker dividing the country into north and south. It winds its way through the 10 provinces of Qinghai, Tibet, Yunnan, Sichuan, Hubei, Hunan, Jiangxi, Anhui, Jiangsu and Shanghai before reaching the East China Sea. Its fertile ALLUVIAL PLAINs produce great amounts of wheat, cotton, tobacco and silk. The Changjiang or Yangzi River dominates the center of China both north-south and east-west. It is thus one of the major factors affecting China’s future industrialization and food production.

Changjiang means “long river” and that it is. China’s Changjiang is the third-longest river in the world (after the AMAZON and NILE). It is over 3,960 mi (6,300 km) long and comparable in economic importance to the MISSISSIPPI in the UNITED STATES. Originating in the Tanggula Shan of eastern Tibet, the Changjiang passes through and links the fertile Red Basin of Sichuan province with the THREE GORGES and their new and massive hydroelectric project as well as the central food basket provinces of Hunan-Hubeh. It finally exits to the sea at Shanghai. Altogether it links eight provinces, several major urban and industrial cities and innumerable ecological regions.

The Changjiang is China’s longest navigable river; ocean-going ships are still able to pass as far inland as the Municipality (an autonomous city) of Chongqing. It also is China’s major hydroelectric focus. The Three Gorges Project is designed to provide clean electric power to all of Sichuan and as far eastward as the Shanghai economic cluster. Just from Sichuan to Shanghai, the Changjiang corridor produces 40 percent of the nation’s grain, including 70 percent of the rice, 33 percent of the cotton, 48 percent of the freshwater fish, and over 40 percent of the total industrial output, which is likely to increase significantly with completion of the Three Gorges project. And with an abundance of fresh water, there are plans to divert some to water-deficit areas in North China.

Lake Chad

LAKE CHAD IS A shallow freshwater lake located in west-central Africa. Only 23 ft (7 m) at its deepest, it is 820 ft (250 m) above sea level, and was once larger than the state of VERMONT. In the 1960s, Lake Chad was approximately the size of lake ERIE, one of the Great Lakes located in the Midwest region of the UNITED STATES. In the past 40 years, however, Lake Chad has shrunk to less than the size of RHODE ISLAND. Reasons are twofold: a drier climate, with less water replenishment by monsoons; and water siphoned off for agricultural irrigation purposes has quadrupled to provide for the 20 million people living in the four countries (Chad primarily, but also CAMEROON, NIGER, and NIGERIA) that include Lake Chad in their borders.

To illustrate the lake’s reduction: Its surface area measured 10,000 square mi (25,000 square km) in 1963 but had shrunk to 839 square mi (1,350 square km) by 2001, causing the lake to become one-twentieth of its original size. The most significant decrease occurred between 1973 and 1987. Still, Lake Chad is the fourth-largest lake in Africa, with only Lakes VICTORIA, TANGANIKA, and MALAWI superior in size. It is a central point of the region for many reasons, including the important archaeological discoveries found nearby. This region contains some of the earliest evidence of hominids; the area has been occupied, nonstop, since perhaps 500 B.C.E.

Other pivotal roles of the lake and its perimeter include the area’s prominence in the region’s trade, the massive irrigation projects that rely upon its waters, and the flora and fauna that grow—and the wildlife that live—nearby. Fish quantities, however, are significantly decreasing, a concern since fish provide a source of protein for the population.

Because of the decrease in fish, along with other signals of environmental distress, the lake and surrounding basins have been declared a “disaster zone.” A research paper exploring the devastation, “Human and Natural Impacts on the Water Resources of the Lake Chad Basin,” appeared in the American Geophysical Union’s Journal of Geophysical Research in 2001. Britain’s Department for International Development in Nigeria, however, offers a more optimistic outlook.

According to their experts, the shrinkage of Lake Chad has created more farmland, land that is fed by the lake when its boundaries expand during rainy weather. Leftover fish manure fertilizes this farmland, adding to fertility, and this combination allows farmers to survive three-month drier periods. Significant famines have not occurred in this region, and people living by the lake are effectively fed by agriculture.

Central Business District

A CENTRAL BUSINESS District (CBD) is the nucleus or downtown of an urban area that contains the main concentration of commercial land use, with the highest percentage of retail shops, offices, and services such as banking and finance. Large cities are characterized by distinct retail sub-areas that have their own “walking district.” Some specialized clusters of nonretail activities can be found, such as law offices, medical facilities, and offices services. Applicable to any city, the CBD is found in global cities with international and financial business centers such as NEW YORK, LONDON, TOKYO, PARIS, Frankfurt, Zurich, Amsterdam, LOS ANGELES, HONG KONG, and SINGAPORE. In global cities where the CBD is strong, advantages include local expertise, world-class technology, specialized knowledge, and networking capabilities. There are slight differences in the patterns of CBDs around the world.

The concentration within a CBD is associated with high land values because of high accessibility. These characteristics of urban location are similar to the William Alonso model. The CBD has been identified as a district area after the general theories of city structure in the 20th century. There has been no specific defined geographic area for a downtown, unlike the boundaries of a city for example. In their pioneer work, the urban geographers, Raymond Murphy and James Vance (1954), found a number of indices by which the CBD could be physically delimited. However, their method required a large amount of land use and building use data, and thus it was rarely used. The CBD has the highest concentration of land uses and in general the tallest nonresidential buildings. It is spatially structured internally, with different specialist areas to benefit from the external economies associated with agglomeration. Vertical segregation exists also with uses that can afford the highest rent on the ground floors of high-rise buildings.

Methods for the delimitation of the CBD include mapping land use intensities referring to the central business height index, recording the percentage of the land uses of each floor of each building within the CBD, and calculation of high-level pedestrian flows. The Manhattan CBD is, for example, characterized by very high offices blocks and a lack of residential buildings, which has the result making the area deserted after offices hours. In the 1970s, planners introduced the development of a resident-friendly concept, such as gentrification, to bring night life back to the downtown area. The Marunouchi District, the heart of Tokyo’s CBD located near the Tokyo Station (through which more than 700,000 passengers each day commute), is characterized by the new massive Marunouchi building complex. It attracted more than 13 million visitors during its first six months.

However, characteristic of many CBDs, the three Tokyo core wards of Chiyoda, Chuo, and Minato have a nighttime population of 268,000 persons but a daytime population is 2.341 million persons. Some large cities as London and Tokyo have several CBDs. Moreover, if the CBD remains a strategic area for leading industries, it is reconfigured by technological and economic change. Many CBDs are facing several problems, such as congestion that has led to parking restrictions, and decline not only with the increasing growth of out-of-town developments with shopping centers and office parks very close to major highway intersections, but also with the cyclical decrease of business activity.

In New Orleans, LOUISIANA, after the oil industry collapse in the 1980s, almost all office inventory was abandoned as companies went out of business; and the occupancy of the CBD only ever achieved 90 percent of the capacity. After the technology bubble burst in San Francisco, CALIFORNIA, office space rates fell as much by half.

Central America Free Trade Agreement

THE CENTRAL America Free Trade Agreement (CAFTA) is a treaty between the UNITED STATES and the countries of Central America (HONDURAS, GUATEMALA, EL SALVADOR, NICARAGUA and COSTA RICA)—what the Russians refer to as the “near abroad.” This is a parallel to the earlier NAFTA (North American Free Trade Agreement). The objective is a free-trade association between the countries of Central America and the United States. It is to replace the Caribbean Basin Initiative (CBI), a unilateral agreement by the United States allowing 80 percent of Central American products to enter the United States with minimal or no duty. The CBI was designed to expire in 2007. This new agreement will focus on the land-based countries and not the islands.

As with NAFTA, the objective of the agreement is to create a common set of rules and standards to regulate commercial trade in both goods and services. It also has the objective of creating an economic environment that will benefit local people and thus create more stable governments. To this end, governments must privatize current government monopolies. Government-owned telecommunications were a major sticking point for Costa Rica, which at the end of 2003 asked for more time to negotiate and adjust. As of October 2003 all countries, except Costa Rica, had reached agreement. Costa Rica sought and was given an extended period for final negotiations.

The United States is the main customer of Central America ($11 billion in 2002—over 43 percent of total exports from Central America). Conversely, the U.S. trade with Central America is more than its trade with INDIA and RUSSIA combined. With the implementation of CAFTA (with or without Costa Rica) this trade is likely to increase rapidly. In addition, there will be many more American companies willing to open new businesses in Central America.

A hidden wild card in all this is the future status of CUBA. It is widely agreed that once the U.S. embargo on Cuba ends, Cuba will become the dominant economic power in the Caribbean Basin. NAFTA and CAFTA may provide sufficient regional cooperation to also provide competitive strength when this happens. It seems that the strategy of CAFTA is to provide a treaty distinct from anything that may occur in the islands.

Central African Republic

DEEP IN THE HEART of the African continent, the LANDLOCKED Central African Republic is on a heavily forested plateau about the size of TEXAS between the Chad and CONGO RIVER basins. It is bounded on the north by CHAD, SUDAN to the northeast, the Democratic Republic of the CONGO (formerly Zaire), CONGO to the south, and CAMEROON to the west. The area has a tropical climate with two annual wet seasons, May-June and October-November. However, in the very dry summer, the Harmattan, a hot, dust-laden wind blows in from the SAHARA DESERT with a saunalike effect in the cities.

From the 1500s until the 1800s, the area was ravaged by the slave trade. In 1894, the French occupied the region, then called Oubangui-Chari, and combined it administratively with Chad, GABON, and the Middle Congo to become French Equatorial Africa. In 1946, the French granted internal self-government. On August 13, 1960, President David Dacko proclaimed complete independence but alarmed the Western powers when he aligned with communist CHINA. He was overthrown in a coup on December 31, 1965, by Jean-Bédel Bokassa, his cousin and army chief of staff, who then declared himself Emperor Bokassa I.

Allegations of brutality and excess characterized his regime, with Amnesty International charging he participated in the massacre of 80 schoolchildren. In 1979, he was ousted by a coup supported by French paratroopers. Dacko returned to power, but an army coup deposed him again. From 1996 to 1998, violence between the government and rebel groups prompted the United Nations to send in an all-African peacekeeping force. Although elections were held in September 1999, repeated coups have followed.

Although the nation is rich in natural resources, including diamonds, gold, and oil, more than 70 percent of its citizens are subsistence farmers working only 3 percent of the land. Large stands of timber cover 75 percent of the country and surveys suggest extensive additional mineral wealth. Poaching has diminished the republic’s reputation as one of the last great wildlife refuges and the populace suffers from a high mortality from AIDS, with 13 percent of the population HIV positive. Life expectancy is 41.71 years.

The official language is French, but Sangho is used for commerce and intertribal communication between 80 ethnic groups, of which the largest are Baya (34 percent), Banda (25 percent), Nabandi (11 percent), Azande (10 percent), and Mbaka (5 percent). In July 1990, a decree gave the nation’s 10,000 pygmies full citizenship. A small European community remains, the majority of which are French or Portuguese descendants. Christians account for 83 percent of the population, of which 33 percent are Roman Catholic and 50 percent are Protestant. An estimated 12 percent of the population follows animist traditions and 3 percent are Islamic.

Aneroid Barometer

Aneroid barometers measure barometric pressure through mechanical rather than hydraulic means. First investigated in 1795 by Nicolas-Jacques Conté and patented in 1845 by French physicist Lucien Vidie, the basic aneroid barometer does not consist of a glass tube filled with mercury, but instead contains a metal chamber, a coiled spring, a shaft with bar arm, and a gauge calibrated in both inches and millibars. Any increase or decrease in atmospheric pressure causes the thin walls of the chamber—or sylphon, as it is correctly known—to contract or expand respectively. Tightly wound inside the sylphon, the spring in turn reacts by either opening or closing, while rotating the thin shaft and its attached arm to a given point on the dial. From there the current barometric pressure can be noted and its degree of change from its last position observed. Favored by meteorologists, scientists, and mariners because of its portability and ease-of-use, the basic aneroid model remains in widespread use around the world despite longstanding concerns regarding its precision and reliability in certain weather conditions.

More sophisticated aneroid barometers employed by the National Hurricane Center (NHC) and the Joint Typhoon Warning Center (JTWC) are constructed from alloys (such as nickel-silver or silver- brass) to compensate for changes in external temperature and are equipped with digital displays instead of the traditional gauge or dial configuration. Aneroid barometers have also been modified for use in microbarographs and for deployment in hurricane-hunting weather-reconnaissance aircraft such as the SUPERFORTRESS B-29 the NEPTUNE P2V-3W, and the ORION WP-3.

Anemometer

An instrument used to measure wind speed. Greek philosophers in the first century b.c. may have been the first scientists to devise an instrument for determining wind speed and direction. Spurred by Aristotle’s philosophical investigations into the nature of weather, Athenian sky watchers constructed an octagonal “Temple of the Winds” in a rudimentary effort to link particular wind directions with certain atmospheric conditions. One end of a large rooftop weathervane faced into the prevailing winds, while the other simultaneously pointed to one of eight sculpted bas-reliefs on the temple’s facade. Besides indicating the sort of weather to be expected from the wind in question, the reliefs—decorated with faces of different meteorological deities—gave a hint of wind speed by alternating their facial expressions from panel to panel. One god’s tightly closed mouth, for instance, might indicate no wind, while another’s ballooning cheeks and pursed lips gave warning of an impending storm.

For all of its interpretive artistry, however, the Temple of the Winds ultimately failed to measure wind speed with any serious degree of quantifiable certainty. It was not until the British physicist Robert Hooke introduced his relatively simple anemometer in 1667 that anything close to an accurate measure of wind speed could be achieved. Hooke’s rather ingenious anemometer, which operated on the same principle as a pendulum, featured a broad square plate, a swinging arm, and a calibrated arc-shaped scale. The flat plate was connected to one end of the pivot arm, which in turn was attached to the top of a vane that swiveled, thereby allowing the entire mechanism to remain turned into the wind at all times. As wind speed increased, the flat plate was lifted upward. The pivot arm rose with it to permit the user to gauge simply where the arm paused on the calibrated scale and the degree of its swing.

Hooke’s highly effective anemometer remained in general use until the mid-1840s when a new prototype, designed by Irish astronomer John Robinson, was unveiled at Dublin. Robinson’s anemometer, which recorded wind speed by measuring how many miles of wind moved past the device in a five-minute time period, featured the now-familiar quartet of four hemispherical cups fitted to the ends of two intersecting crossarms. These arms were in turn connected to a hub atop a spinning vertical shaft. The shaft itself was attached to a calibrated gear box that operated a small dial from which wind speed could be read with an accuracy never before possible.

While the Robinson-type anemometer remains standard equipment for weather bureaus across the world, numerous design modifications over the years have vastly improved its basic workings. There are now two-and three-cup models in use, and the geared dial has been replaced by digital readouts and sophisticated graphing systems like those used for measuring earthquakes. New, high-tensile strength mounting systems have also been devised to reduce the possibility that the fragile anemometer will be carried away (as has happened many times in the past) by a tropical cyclone’s relentless winds.

Tropical Storm Ana

North Atlantic Ocean, April 21–24, 2003 

A preseason surprise, Tropical Storm Ana formed to the south-southeast of Bermuda on April 21, 2003. It was the earliest tropical cyclone formation in the North Atlantic since Subtropical Storm One formed on January 18, 1978, and the first April tropical cyclone on record in the Atlantic basin. A more powerful system than the 1978 incarnation, Tropical Storm Ana developed from a subtropical storm that had originated on April 20 and possessed a central pressure of 29.41 inches (996 mb) and 52- MPH (84-km/h) winds. A short-lived system, Ana tracked almost due eastward into the mid-Atlantic, where it essentially merged into a frontal system and dissipated three days later. While Ana never made landfall, it did indirectly cause the deaths of two mariners in Florida whose craft was overturned by its large swells on April 20.

The 2003 North Atlantic system was the fourth to bear the name Ana. The first appeared on June 19, 1979, in the form of a tropical storm that had originated in the western North Atlantic Ocean, drifted almost due westward across the Windward Islands, and entered the Caribbean Sea before dissipating on the 24th of the month. At one time a relatively powerful tropical storm with a central pressure of 29.67 inches (1005 mb) and 58-MPH (93-km/h) winds, Tropical Storm Ana had weakened as it crossed the Windward Islands, its central pressure rising to 29.88 inches (1,012 mb) and its wind speeds dropping to 40 MPH (64 km/h).

While avoiding landfall for the duration of its existence, the second Tropical Storm Ana was a marginally more intense tropical cyclone than its 1979 predecessor. Born over the mid-Atlantic Ocean on July 15, 1985, Ana recurved to the northeast around Bermuda and sped into the extreme North Atlantic before fading off the Canadian Maritimes on July 19. A central pressure of 29.41 inches (996 mb) produced sustained winds of 69 MPH (111 km/h), but no deaths or damage assessments.

On June 30, 1991, a strengthening Tropical Depression Ana—the third such system to bear the name—sliced across the Florida peninsula, its central pressure of 29.88 inches (1,012 mb) producing 23- MPH (37-km/h) winds and pounding rains. Before dissipating over the Atlantic on July 5, 1991, Ana

reached tropical storm intensity, with a central pressure of 29.52 inches (1,000 mb) and sustained winds of 52 MPH (84 km/h). No lives were lost due to Ana’s early-season passage across Florida. The name Ana has been retained on the rotating list of North Atlantic tropical cyclone identifiers, and

is scheduled to reappear in 2009.

Tropical Storm Allison

Southern United States, June 4–18, 2001 

The first named tropical cyclone of the 2001 North Atlantic hurricane season, Tropical Storm Allison delivered deluging rains to portions of southeastern Texas and Louisiana between June 5 and 11, 2001. Allison dropped between 10 inches (250 mm) and 30 inches (760 mm) of rain, claiming 24 lives and causing more than $5 billion in property losses.

The most costly tropical storm yet recorded in the United States, Tropical Storm Allison developed in the Gulf of Mexico on June 4, 2001, from a subtropical low pressure system that had originated over Mexico’s Bay of Campeche. On June 5, five days after the official start of the 2001 hurricane season and as the system meandered some 130 miles (200 km) south of Galveston, Texas, the National Hurricane Center (NHC) upgraded the system to tropical storm status, awarding it the name Allison. Carried westward, Allison’s sustained 60-MPH (95-km/h) winds and heavy rains came ashore at Freeport, Texas, during the midafternoon hours of June 5. Bearing a central pressure of 29.52 inches (1,000 mb) and surging rains,

Allison’s poorly organized circulation system traveled slowly over northern Texas, then, on June 8, drifted southward, bringing enormous precipitation counts to the Houston metropolitan area. In the Port of Houston, one of the nation’s busiest maritime trade nodes, some 37 inches (940 mm) of rain was recorded during Allison’s erratic passage inland. By June 9, streams and drainage canals across eastern Texas were quickly overflowing their banks, and large sections of downtown Houston— including its city hall—were flooded when the Buffalo and White Oak bayous became saturated.

Several medical facilities associated with the Texas Medical Center were evacuated as flash flooding caused by Allison’s record-setting rainfalls disrupted utilities and destroyed medical equipment. In some instances, Allison’s powerful downpours hampered the evacuations as they closed major arteries and freeways in the city. Some 70,000 residential and commercial structures in and around the Houston area experienced partial or total flooding, while in an underground parking garage in Houston, a woman drowned while trying to retrieve her automobile. All told, 21 people died in Houston, making Allison one of the deadliest tropical cyclones to have affected Texas in over a decade.

Hurricane Allison

Cuba–Southern United States, June 2–5, 1995 A minimal Category 1 hurricane,

Allison became the earliest mature-stage hurricane in recorded history to strike the mainland United States when it came ashore at Apalachicola, Florida, on the morning of June 5, 1995. The 1995 hurricane season’s first tropical cyclone Allison originated as a tropical depression 150 miles (241 km) northeast of Honduras on June 2. Carried almost due north at between 10 and 14 MPH, the strengthening tropical storm slid across the western tip of Cuba on June 3, bringing steady rains and 50-MPH (81-km/h) winds to the island. One man was killed in Havana.

Clearly bound for the Florida Panhandle, Allison continued to intensify throughout that day and night, prompting that state’s civil defense authorities to post hurricane warnings from Pensacola to Clearwater and to commence the evacuation of some 5,000 particularly vulnerable coastal residents.

Shortly before 11 o’clock on Monday morning, June 5, Allison made landfall in Taylor County, approximately 45 miles (72 km) southeast of Tallahassee. With a fairly mild central barometric pressure of 29.05 inches (984 mb), Allison’s fitful 75-MPH (121-km/h) gusts buffeted trees and severed power lines, leaving an estimated 48,000 residents in seven counties with neither electricity or telephone service. Along a 150-mile (241-km) stretch of Florida’s Big Bend, Allison’s eight-foot (3-m) storm surge flooded more than 65 surfside homes and caused extensive water damage to three hotels and a restaurant on the barrier island of St. George.

In Apalachicola, three fishing boats were swamped at their piers while five-inch (127-mm) rainfalls threatened the bay’s fragile oyster beds. The soaring Bryant Patton Bridge, linking Apalachicola with St. George Island, was closed for much of the storm’s duration as streaming seas washed debris onto its low-lying approaches. Further inland, isolated flooding damaged three houses and a grocery store and inundated a trailer park. Quickly moving into southwestern Georgia on the afternoon of June 5, Allison’s downgraded winds spawned a tornado that touched down in the town of St. Marys, gutting an empty grade school at the Kings Bay Naval Submarine Base. No serious injuries or deaths were

reported in either Florida or Georgia.

With some $785,000 in property damage to its credit, Allison was largely dismissed by survivors as one of the mildest hurricanes to have ever struck Florida. Nevertheless, it was in turn touted by scholars as the earliest storm of hurricane intensity to have made landfall in the United States since consistent record-keeping began in 1889. Although in the intervening 120 years no less than eight storms reached hurricane strength before June 10, only three—Hurricane Alma, June 9, 1966, an unnamed tropical storm in late May of 1970, and Hurricane Allison— ever touched the nation, making them official, record-breaking landfalls. Bearing a central pressure of (1,001 mb) and 52-MPH (84-km/h) winds, Tropical Storm Allison made landfall in Texas on June 26, 1989. Formed on June 24, the system—the first to bear the name Allison—caused no deaths or major property losses in Texas.

The name Allison was retired from the rotating list of North Atlantic tropical cyclone names in 2001.

Cayman Islands

THE CAYMAN Islands are one of the UNITED KINGDOM few remaining colonies in the CARIBBEAN SEA. The group, lying roughly 150 mi (250 km) northwest of JAMAICA, consists of three main islands, Grand Cayman, Little Cayman, and Cayman Brac. They were first named Las Tortugas by Christopher Columbus in 1503 because of the abundance of turtles, and turtles remain one of the chief natural features of the islands. Later, the islands were named for their other large reptile residents, lagartos (alligators), then caymanas, the Carib word for “crocodile.”

The islands are low-lying limestone formations, surrounded by coral reefs, providing habitat for abundant marine life. Because the soil is so dry and thin, the islands have never been able to grow much agriculturally, and there are no rivers or streams. The islands are the tops of a submarine mountain ridge that extends from BELIZE to CUBA. Parallel to the Cayman Ridge is the Cayman Trench, the deepest part of the Caribbean Sea—Bartlett Deep plunges over 18,000 ft (5,455 m).

An abundance of healthy coral reefs draw numerous divers each year, particularly to the Bloody Bay Marine Park off of Little Cayman, one of the most diverse coral walls in the area. Cayman Brac and Little Cayman lie about 89 mi (144 km) northeast of Grand Cayman, and have a more varied topography, especially on Cayman Brac, with its high bluff, sheer cliffs, and caves. Grand Cayman is flatter and has a large, shallow reef-protected lagoon, the largest area of inland mangrove in the Caribbean. Almost all of the population lives on Grand Cayman. Little Cayman has almost no population but is home instead to nesting birds.

The Caymans formed part of the Spanish colony of Jamaica from the 16th century but were never settled and passed with Jamaica to the British crown in 1670. British presence was established mostly as a refueling station (for food and water provisioning), and the islands were administered as an appendage of Jamaica until that island’s independence in 1962. Shark and turtle farming was the only economic activity until the development of tourism and finance in the later 20th century.

Today, the Cayman Islands are the fifth-largest offshore financial center in the world, employing most of its labor force and providing its residents with one of the highest standards of living and no direct taxation. In 1998 there were more than 40,000 companies registered in the Cayman Islands, including nearly 600 banks. Registration of ships and corporation brings in a large amount of government revenue. About 70 percent of the gross domestic product comes from tourism: More than 1.2 million visited in 1997, mostly from North America. A constant danger, however, lurks in the many Caribbean storms and hurricanes (cyclones)—Hurricane Gilbert, the most powerful storm recorded in the Western Hemisphere, hit the Caymans in 1988. A Category 5 storm, Gilbert’s sustained winds of over 155 mi (249 km) an hour leveled nearly every structure on the islands.

Caucasus Mountains

THE CAUCASUS MOUNTAINS are the highest mountain range in Europe, but lie at the very eastern extremity of what geographers consider to be Europe. In fact, the dividing line traditionally used to divide Europe from Asia runs directly through the center of the range.

Forming both a barrier and a connector for civilizations between the BLACK and CASPIAN seas, and between the MIDDLE EAST and the STEPPEs to the north, the cultures of the Caucasus region have occupied a central place for trade and cultural exchange for over 2,000 years. The range’s isolated valleys have served as a haven for refugees and immigrants from many areas, resulting today in one of the most ethnically and linguistically diverse regions on Earth. 

The two major ranges of the Caucasus, the Great Caucasus and the Lesser Caucasus, stretch east to west for nearly 550 mi (900 km) from the eastern shore of the Black Sea to Baku on the Caspian. Elevations generally rise from both ends towards the central range, in which the highest peaks are located, including Mount ELBRUS, the highest peak (18,506 ft or 5,642 m). The various ranges and subranges are similar in their mountain characteristics: jagged and generally impassable. 

Climatically, however, west and east differ dramatically, due to the effects of moisture off the Black Sea and the contrasting dryness of the Caspian. As a result, the western ranges tend to have a subtropical climate, with heavy vegetation, while the eastern part of the range is semidesert and barren. The Caucasus Mountains share many characteristics with the ALPS, but their peaks are generally much taller, averaging 6,000 to 9,000 ft (2,000 to 3,000 m)—over 20 summits are higher than Mont Blanc. Its ridges are mostly parallel, running from west-northwest to east-southeast, but are broken up by horseshoe-shaped ridges with glacier-filled basins. Many of these are unstable, subject to frequent landslides and avalanches. Most of the ridges are more continuous than those of the Alps, resulting in a greater barrier, with only one major pass—through the dramatic Daryal gorge—and several smaller ones that are usually obstructed by snow. As a result of several of these features, the Caucasus Mountains are generally more inhospitable than the Alps and have a more wild and austere quality.

The Caucasus ranges were formed in the same manner (and at roughly the same time) as the Alps, through tectonic plate collision between the Arabian Plate and the Eurasian Plate. This movement continues today, manifesting itself through regular earthquakes. Many years ago there was volcanic activity in the region, creating some of the tallest cones (like Elbrus), but these volcanoes are currently extinct, with the exception of the active mud volcanoes of the Apsheron Peninsula, which juts 53 mi (85 km) into the Caspian Sea. It is here where the most important of the region’s natural resources are located—the offshore oilfields of AZERBAIJAN. Other oil resources are found on the northern slopes, near the cities of Grozny and Krasnodar. At the western extremity of the range, the Caucasus also extend a bit further than the land they occupies, forming the low mountains of the Taman Peninsula, which nearly joins with the Kerch Peninsula of the Crimea, across the mouth of the Sea of Azov. 

The Great Caucasus range is divided from the Lesser Caucasus by a parallel valley, the Transcaucasian depression, averaging 60 mi (100 km) in width. This depression connects the Black Sea coast with the Caspian Sea, where elevations dip below sea level. The depression is divided in two by a low range perpendicular to the main ranges, the Surami, which forms the climatic barrier between the moist west and the dry east. To the west of this range lies the Colchis Lowlands, the “Riviera of the Caucasus,” with grapes and olives and holiday resorts. To the east lies the Kura Lowland, dominated by the Kura River, the longest river in the Caucasus, which flows out of the Armenian Highlands, past the industrial city of Tbilisi to the Caspian Sea near Baku. Near its mouth, the Kura is joined by the Araks River, which starts in eastern TURKEY and forms the border of ARMENIA and Azerbaijan with Turkey and IRAN to the south. This basin was actually part of the Caspian Sea in times of higher water levels. Other major rivers of the Caucasus region flow north, cutting gorges through the Great Caucasus: the Kuban, which flows into the Black Sea, and the Terek and Sulak, which flow across Dagestan into the Caspian.

Caspian Sea

THE CASPIAN SEA IS ONE of the world’s largest bodies of water, situated in a depression between RUSSIA, KAZAKHSTAN, TURKMENISTAN, IRAN, and AZERBAIJAN. It is unique among the world’s inland seas in that it is completely isolated from the rest of the global ocean and has a distinctive continental climate which gives the area extremes in temperature, from very hot summers to very cold winters.

Several rivers flow into the Caspian Sea, most notably the VOLGA and the Ural in the far north and the Terek, Sulak and Kura rivers from Daghestan and the Caucasus to the west. In fact, by including the entire Volga River Basin, the Caspian has the largest catchment area in Europe (1.4 million square mi or 3.5 million square km). But no rivers flow out of the Caspian, and most of the water is lost through evaporation. This is aided by the fact that much of the Caspian is very shallow, particularly in the north and the east. These parts are also very low-lying: The lowest point in Europe is the surface of the Caspian Sea, 89 ft (27 m) below sea level. Most of the eastern coast of the Caspian Sea is dry, with the extreme southeastern corner leading directly onto the Kara Kum Desert. In contrast, the southern and western shores are more steep, culminating in the nearly vertical walls along the southern coast where the ELBURZ and Talysh mountains of Iran come down to the sea. The seafloor drops most dramatically in this region as well, with the Caspian’s greatest depths over 3,300 ft (1,000 m). The southwestern areas are also mountainous, consisting of the easternmost reaches of the CAUCASUS mountain ranges.

The Caspian stretches for over 620 mi (1,000 km) from north to south, and between 125 and 250 mi (200 and 400 km) east to west, totaling 143,270 square mi (393,000 square km) in area. It holds much of the world’s lacustrine (lake-associated) water: 18,881 cubic mi (78,700 cubic km) of mixed salty and brackish fresh water. The salinity of the Caspian is heavily dependent on the level of flow from the Volga.

Cartogram

ONE OF THE LIMITATIONS of the traditional paper map is that real world areas with large populations are usually small in physical size and therefore represented as small area units on a map. As such, traditional paper maps have tended to mask geographic patterns in small area units that are of importance and interest on the map. The cartogram was developed to overcome this challenge.

A cartogram is a map or diagram that depicts attributes of geographic objects in direct proportion to the area or length of the objects. In linear cartograms, the length (distance or travel time) of geographic objects is scaled in proportion to the attribute being mapped. Likewise, in area cartograms, the area of a geographic object is scaled in proportion to an attribute.

For example, if an area cartogram uses the area of a country to depict the magnitude of its population (the attribute), then country A, with twice the population of country B, will be represented on a cartogram with an area twice that of country B. Since the cartogram does not represent geographic space, but alters the size of objects in proportion to an attribute, it is not considered a scaled map. As such, the cartogram does not always appear visually similar to a map.

Cartograms are of three types: noncontiguous, contiguous, and Dorling cartograms. Noncontiguous cartograms are the simplest and allow the geographic objects to be detached from their adjacent neighbors. This detachment permits the objects to expand or contract their area without distorting their natural shape. Contiguous cartograms are more difficult to construct because neighboring objects must remain in contact, resulting in a distortion of shape.

In Dorling cartograms the geographic objects are replaced with a uniform nonoverlapping shape, such as a circle, where the area of the circle is proportional to the attribute being represented. Each cartogram type presents the attribute of geographic objects from a different perspective. Also, each type of cartogram requires a different level of effort from the reader to understand the structure and content of the information being communicated.

In addition to the three pure forms of cartograms, there exist pseudo-cartograms, or false cartograms. Pseudo-cartograms do not strictly follow certain cartogram rules. For example, instead of enlarging or shrinking objects directly, Waldo Tobler pioneered an approach where the distance connections between the objects are transferred to a reference grid such as latitude and longitude to maintain directional accuracy among the objects. But in so doing, extensive errors are created in the real object size. However, pseudo-cartograms are useful because they are regarded as an intermediate stage that is easily created by a computer and can be later modified by a cartographer toward the development of a pure continuous cartogram.

Caribbean Sea

THE CARIBBEAN SEA is a suboceanic BASIN in the western ATLANTIC OCEAN. The sea covers just over 1 million square miles (2.6 million square km) and contains numerous islands. The islands, which vary greatly in size, cover some 91,000 square mi (235,688 square km). CUBA is by far the largest at 44,000 square mi (113,959 square km). In contrast, ANGUILLA has a mere 100 square mi (259 square km).

The islands can be divided into four groups. First are the BAHAMAS, consisting of more than 700 small islands. Second are the Greater Antilles, made up of Cuba, Hispaniola, PUERTO RICO, and JAMAICA and comprising more than 80 percent of the total land area of the Caribbean. Third are the Lesser Antilles, comprising two arcs of islands. An inner arc is made up of volcanic islands, while an outer arc is made of coral limestone islands. Fourth are the South American offshore islands of ARUBA, Bonaire, Curaçao, TRINIDAD, and TOBAGO.

Several geographic characteristics define the Caribbean. One is the insular nature of the region. The fact that the region is made up of many small islands has shaped the Caribbean’s history. The small size of the islands made it virtually impossible for the native inhabitants to resist European attacks, enslavement, and disease. The large number of islands allowed several European powers to colonize the region beginning in the late 1400s. The presence of various European countries has contributed to the cultural diversity of the Caribbean Sea. Furthermore, because of the fragmentation of the region, there was historically more interaction and contact between the islands and the metropolitan powers than among the islands.

The small size of the islands is a second important feature. While the islands are small, many of them have relatively large populations, making them some of the most densely populated areas of the Western Hemisphere. The small size of Caribbean nations has led to numerous problems. Land is often scarce and internal markets are small, forcing countries to rely on imports. Per capita government spending in areas such as education, healthcare, and welfare is all extremely high in the

Caribbean. 

A third defining characteristic is the Caribbean’s location in a maritime tropical air mass. Average temperatures in the region are high at around 80 degrees Fahrenheit. There is little seasonal change throughout the Caribbean. Precipitation in the region varies from island to island. Low-lying islands receive very little rainfall, while those with higher volcanic peaks receive more. Precipitation even varies on each island, as the northeastern sides tend to be wetter than the southern sides.

Hurricanes are a fourth characteristic of the Caribbean. They are a regular occurrence in the region, arriving between June and November of each year. The hurricanes form in the eastern Atlantic Ocean and follow the trade winds to the Caribbean, where an average of eight strike each year. Hurricanes are often destructive, damaging property and crops. In 1963, Hurricane Flora took more than 7,000 lives in the Caribbean.

A fifth characteristic is environmental degradation. The introduction of export agriculture in the form of sugarcane production ushered in environmental problems in the Caribbean. As European plantation owners put their African slaves to work clearing forests, native flora and fauna often disappeared. Such deforestation led to problems such as increased risk of erosion and drought. Fertile soil was quickly exhausted. By the 20th century, poverty and tourism both contributed to these environmental problems in the Caribbean.

A sixth feature of the Caribbean is its strategic location. It serves as a link between Europe and Latin America. The Spanish used the Caribbean as a base to conquer the mainland areas of the Americas. Beginning in the late nineteenth century, the UNITED STATES began to become involved in the Caribbean because of its strategic importance. After the opening of the PANAMA CANAL in the early 20th century, the region’s strategic significance for military and economic matters greatly increased.

Hurricane Allen

Eastern Caribbean–Southern United States, August 4–10, 1980 

One of the most intense Category 3 hurricanes on record, Allen spent August 4 through August 10, 1980, beating a trail of destruction through the eastern Caribbean Sea, Hispaniola, Cuba, Mexico, and the gulf coast of Texas. Allen intensified to Category 5 status on the Saffir-Simpson Scale three times during its 1,200- mile (1,920-km) trek from the Cape Verde Islands. Its lowest central pressure, 26.55 inches (899 mb), was recorded off the northeast tip of Mexico’s Yucatán Peninsula on the evening of August 7. Before dissipating into a string of tornadoes over south-central Texas on August 10, Allen caused close to $1 billion damage to six countries and left 272 people dead.

A classic Cape Verde Storm, Allen was born as a low-pressure tropical disturbance off the northwest coast of Africa on August 1. Carried westward by the equatorial trade winds, Allen rapidly intensified over the mid-Atlantic’s warm tropical waters. By August 3, as the hurricane bore down on the islands of Barbados, St. Lucia, and Dominica, weather reconnaissance flights through its eye indicated barometric pressures as low as 27.23 inches (922 mb) and intermittent winds upward of 200 MPH (320 km/h). Touted as one of the twentieth century’s most potentially dangerous hurricanes, Allen whisked across Barbados and St. Lucia on August 4. Winds of 130 MPH (209 km/h) tore into St. Lucia’s vital banana plantations, uprooting trees, leveling houses, and killing 16 people. On the resort island of Barbados, Allen’s 11-foot (4-m) storm surge pounded empty beachfront hotels, smashing windows, flooding swimming pools with seawater, and washing away yacht piers.

On August 5, Allen careened across southern Haiti. Sustained winds of 120 MPH (193 km/h) devastated a large portion of the country’s coffee crop, while torrential rains spawned flash floods that killed an estimated 220 people. Brushing past the island of Jamaica on the morning of August 6, Allen’s slightly diminished 100-MPH (161-km/h) winds battered northern cities Port Maria and Port Antonio and unleashed deadly rains that knocked out power lines and bridges in the exclusive Montego Bay enclave. In the resort city of Port Maria, Allen’s enormous storm surge completely demolished two beachside hotels by undermining their concrete pilings. Witnesses claimed the five-story buildings simply toppled forward into the raging surf and disappeared.

After grazing the west coast of Cuba—where 110-MPH (177-km/h) winds forced the evacuation of 210,000 people from low-lying areas on August 7— Allen took aim at Mexico’s vast Yucatán Peninsula. Luxury resorts on the shallow islands of Mujeres and Cozumel were hurriedly evacuated as Allen’s eye swept inexorably up the Yucatán Channel. Although the picturesque islands did suffer some wind and water damage, they were largely spared the full fury of Allen’s passage into the Gulf of Mexico. On the peninsula’s northern face, the hurricane’s strengthening winds stripped foliage from trees and drove large waves onto the beachheads but caused no fatalities.

By the morning of August 8, Hurricane Allen’s eye was centered 52 miles (84 km) due north of the Yucatán Peninsula and headed on a course that would take it across the Gulf of Mexico to a stormy landfall somewhere along the Texas lower coast. During the previous night, the storm’s central pressure had seesawed between a vigorous 27.91 inches (944 mb) and an alarming 26.55 inches (899 mb), one of the lowest barometric readings ever recorded in an Atlantic hurricane. As National Hurricane Center (NHC) officials pored over computer-generated forecasts, trying to determine just where Allen would come ashore, civil defense authorities in Texas began to evacuate a quarter of a million people from the 450-mile (724-km) stretch of coastline between Brownsville and Corpus Christi. Over the agitated waters of the gulf, a squadron of chartered helicopters set to work airlifting hundreds of oil company personnel from deep-sea drilling rigs. 

In one tragic instance, Allen’s extended gale-force winds caused a helicopter to crash into the sea off Louisiana, killing 13 workers. Allen blasted ashore near Corpus Christi, Texas, on August 9, 1980, with a central barometric pressure of 27.91 inches (945 mb). Gusts of 160 MPH (258 km/h) drove before a 10-foot (3-m) storm surge, the highest seen on the coast in a half-century. Allen’s whirring winds and pelting rains stripped buildings of their roofs and siding, crumpled billboards, toppled trees and telephone poles, and caused massive localized flooding. Mountainous waves drove a disabled Liberian tanker, loaded with 280,000 barrels of crude oil, onto a sandbar off Corpus Christi, raising fears of a dangerous oil spill. Coast Guard personnel bravely fought 40-foot (13-m) seas to rescue the tanker’s crew of 37 and to secure the heavily laden ship against the relentless hammering of the ocean. Steadily moving inland across the lower Rio Grande Valley, Hurricane Allen’s downgraded winds spawned numerous tornadoes and caused nearly $1 billion damage to the region’s citrus harvest. Conversely, the storm’s 20-inch rains brought beneficial precipitation to countless farms, ending a prolonged drought that had threatened the valley’s largely agrarian economy.

Allen’s dramatic disintegration would herald the start of an unprecedented three-year hiatus in hurricane activity along the U.S. mainland coasts. Between August 10, 1980, when Allen blew itself out over Texas, and August 13, 1983, when Hurricane Alicia surged ashore at Galveston, no hurricanes threatened U.S. coastal tranquility. The name Allen has been retired from the list of future hurricane names.

Hurricane Alicia

Southern United States, August 14–19, 1983 This moderately powerful Category 3 hurricane’s 115-MPH (185-km/h) winds and 12-foot (4-m) storm tide lashed large portions of south Texas on August 18, 1983. With a central pressure at landfall of 28.41 inches (962 mb), Alicia was the first storm of hurricane intensity to strike mainland United States since Hurricane Allen came ashore near Brownsville, Texas, on nearly the same date in August 1980.

A midseason hurricane that formed over the warm waters of the eastern Gulf of Mexico on August 14, Alicia leisurely intensified before striking the port city of Galveston with diligent fury in the early morning hours of August 18. Damage in the hurricane-prone city of 60,000 was severe. Alicia’s sixfoot (2 m) storm surge, coupled with above-average tides, broke over Galveston’s famed seawall, flooding several low-lying areas of the island city. All electricity and telephone service was cut, and downpours made driving exceptionally hazardous. There were several incidents of looting. Six people were killed, and another 30 were injured in Galveston, but Alicia could have been much worse: The ferocious Great Galveston Hurricane of 1900 killed between 6,000 and 12,000 people, while a lesser hurricane in 1915 breached the newly built seawall and drowned 275 people. The lifesaving benefits of modern construction techniques and hurricane awareness programs were made readily apparent by Alicia’s spirited assault on the one-time “New York of the South.”

Its wind and rain virtually undiminished, Alicia spiraled inland, hammering Houston and its surrounding communities just before midday on August 18. Already reeling from an economic recession brought on by a collapse in oil prices, Houston sustained close to $1 billion in property damage as Alicia’s winds knocked out power lines, uprooted trees, and overturned cars. In downtown Houston, Alicia spawned small tornadoes that pried glass curtain walls away from some of the city’s tallest buildings. Deadly shards of glass and torn aluminum crashed to the street as the wind and rain shattered the glittering facades of the 71-story Allied Bank Plaza building (now the Wells Fargo Bank Plaza) and the 33-story Hyatt Regency Hotel. Forty-two thousand people fled as flash floods invaded their homes; nearly 50 people were arrested for looting. Even though Alicia was downgraded to a tropical storm by three o’clock that afternoon, its damage was so extensive that several days passed before telephone and water services was fully restored. Fifteen people in the Houston area were killed.

On August 19, then President Ronald Reagan

declared both Galveston and Houston disaster areas

and made available several hundred million dollars

in federal funds for emergency relief. The American

Insurance Association later set the total insured property

damage from Alicia at $675 million, although

this figure was eventually adjusted higher. At the

time, Alicia’s $1 billion price tag made it the thirdmost-

costly hurricane in U.S. history. Owing to the

extensive damage wrought by the hurricane, the

name Alicia was retired from the revolving list of

hurricane names the following year.

Hurricane Alice

Caribbean Sea, December 30, 1954–January 6, 1955 

The first North Atlantic tropical cyclone identified with a name taken from the female list of hurricane identifiers, preseason Tropical Storm Alice carved a bizarre trajectory through the southwestern Caribbean Sea and Gulf of Mexico between May 25 and June 6, 1953. A powerful tropical storm whose central barometric pressure of 29.44 inches (997 mb) produced sustained winds of 69 MPH (111 km/h), 

Alice affected Central America and northwestern Cuba before bounding ashore in the Florida Panhandle on June 6. No deaths or significant property losses were recorded. The 1954 North Atlantic hurricane season also opened with a tropical cyclone named Alice—one of hurricane intensity. An early season system, Hurricane Alice delivered 81-MPH (130-km/h) winds and torrential rains to northern Mexico and southern Texas between June 24 and 26, 1954. No deaths or injuries were tallied.

Ironically, the second Hurricane Alice of 1954, commonly known as Alice 2, became one of the few tropical cyclones to originate outside of the standard North Atlantic hurricane season, which extends from June 1 to November 30 of each year. Originating on December 30, 1954, from an extratropical cyclone that had acquired tropical characteristics, and lasting until January 6, 1955, Alice rang in the New Year by delivering a central barometric pressure of 29.73 inches (1,007 mb) and sustained 81-MPH (131-km/h) winds to the island of Grenada, in the Leeward Islands.

Although Hurricane Alice caused tens of thousands of dollars worth of property damage to the Leeward Islands, it also delivered much needed precipitation to the island chain, including Puerto Rico. The last Hurricane Alice observed in the North Atlantic basin occurred between July 1 and 7, 1973. A strong Category 2 system, 1973’s Alice produced a pressure reading of 29.11 inches (986 mb) and sustained, 92-MPH (148-km/h) winds as it tracked along the U.S. eastern seaboard. It remained an offshore system until July 6, when it ground ashore in eastern Newfoundland, Canada, as a powerful tropical storm. A pressure reading of 29.26 inches (991 mb) produced 69-MPH (111-km/h) winds, but caused no deaths or significant damage in the province.

Alice has also been used as an identifier for tropical cyclones in the western North Pacific Ocean. Between May 17 and 21, 1961, four people died as Typhoon Alice twirled ashore at Hong Kong. The name Alice has been retired from the list of North Atlantic tropical cyclone names.

Alex Hurricane

Southern–Eastern United States–North Atlantic Ocean, July 31–August 6, 2004 

The first tropical cyclone of the 2004 North Atlantic hurricane season, and one of only two known North Atlantic tropical cyclones to have reached major hurricane status (Category 3 on the Saffir-Simpson Scale and above) in the cool ocean waters north of 38 degrees, Alex was born off the North Carolina coast on July 31, 2004. Spawned by a weak tropical depression (TD 1) located some 175 miles (282 km) south-southeast of Charleston, South Carolina, Alex slowly drifted to the north-northeast before intensifying into a Category 2 hurricane (with sustained winds of 100 MPH [161 km/h]) on the afternoon of August 3. Passing very close to North Carolina’s picturesque but vulnerable Outer Banks, Alex delivered Category 1 winds and rains to the landmark lighthouse at Cape Hatteras, but remained an offshore system that caused no deaths or injuries in the Tarheel State. 

An extreme gust of 102 MPH (164 km/h) was observed on the Outer Banks on the afternoon of August 3. On August 4, 2004, while situated over the leading expanses of the Gulf Stream some 800 miles (1,285 km) southwest of Newfoundland, Canada, Alex became the most powerful tropical cyclone yet observed north of 38 degrees. Driven by an estimated central barometric pressure of 28.26 inches (957 mb), sustained winds of 120 MPH (195 km/h) lashed the sea surface, generating enormous waves and breaking Hurricane Ellen’s 1973 record of sustained 115-MPH (185-km/h) winds in roughly the same area. 

For four British rowers who had come within 300 miles (483 km) of breaking a 108-year old record for rowing across the Atlantic (55 days) from west to east, however, Alex’s record-setting passage proved a degree of competition they could have done without. A huge wave produced by the hurricane smashed their small, lightweight craft and cast them into the raging sea, where they remained for six terrifying hours before being rescued by a Danish cargo vessel. Alex remained at Category 3 intensity through August 5, before steadily weakening over the chill expanses of the western North Atlantic Ocean.

Between July 27 and August 3, 1998, an earlier Tropical Storm Alex—the first North Atlantic tropical cyclone to be dubbed Alex—produced a minimum pressure reading of 29.52 inches (1,000 mb) and sustained 52-MPH (84-km/h) winds, but remained to the east of the Leeward Islands, over the open Atlantic. The name Alex has been retained on the rotating list of North Atlantic tropical cyclone names and is scheduled to reappear in 2010.

Alberto Tropical Storm

Southern United States, July 3–7, 1994 

Between 1982 and 2006, five North Atlantic tropical cyclones have been identified with the name Alberto. Of these systems, two were of hurricane intensity, while the remaining three were classified as tropical storms. Less than three days after the official start of the 1982 North Atlantic hurricane season, the first Hurricane Alberto originated over the warming waters of the extreme western Gulf of Mexico on June 2, 1982. At its peak a powerful Category 1 hurricane, a meandering Alberto’s central pressure reading of 29.08 inches (985 mb) produced sustained winds of 86 MPH (138 km/h) and heavy rains over Mexico’s Yucatán Peninsula, western Cuba and southern Florida, but caused no deaths or serious injuries.

On August 8, 1988, a weak Tropical Storm Alberto chugged ashore in Newfoundland, Canada, delivering 40-MPH (64-km/h) winds and a central pressure of 29.58 inches (1,002 mb) to the province’s rocky but picturesque coastline. Formed off the coast of Georgia on July 5, Tropical Storm Alberto tracked to the northeast, brushing past North Carolina’s Outer Banks as it followed the nourishing waters of the Gulf Stream, northward. No deaths or injuries were reported in Tropical Storm Alberto’s wake. 

Even though its 60-MPH (97-km/h) winds were not of hurricane strength when it first came ashore at Destin, Florida, on July 3, 1994, tropical storm Alberto was later responsible for some of the worst flooding to strike neighboring Georgia in almost a century. Originating off the northwest coast of Cuba on June 30, Alberto steadily moved north across the Gulf of Mexico on a course that closely paralleled that of a 1919 unnamed tropical storm that began in roughly the same place and at about the same time in the hurricane season. As was the case in the earlier storm, Alberto, with a central barometric pressure of 29.32 inches (993 mb), made a midmorning landfall in the vicinity of Pensacola with winds of less than hurricane intensity but bearing immense quantities of tropical precipitation. At Fort Walton, Florida, Alberto’s 66-MPH (106-km/h) gusts created isolated power outages while whipping longleaf pine trees and road signs, but it caused no fatalities.

While coastal flooding ruined that year’s valuable oyster harvest in Apalachicola Bay, it was not until Alberto moved inland, where it collided with an entrenched high-pressure system over the southern United States, that the storm’s torrential rains were finally unleashed on July 5. Americus, Georgia, received as much as 21.1 inches (533 mm) of rain in a single 24-hour period, causing the Flint and Ocmulgee Rivers to overrun their banks quickly. Forty thousand people in Albany, Georgia, were forced to seek higher ground when steadily rising floodwaters inundated their homes. Cemeteries burped up their caskets, and budding cotton fields were washed clean of crop and topsoil alike. Thirty-one people were killed, and hundreds of millions of dollars in property damage were assessed in Tropical Storm Alberto’s wake.

Between August 4 and 23, 2000, Hurricane Alberto tracked a long and convoluted course across the North Atlantic basin. Originating near the western African coast, Alberto tracked to the northwest, executed a large loop to northeast of Bermuda, then moved northward into the North Atlantic. At its peak a hurricane of Category 3 intensity, Alberto’s central pressure of 28.05 inches and sustained winds of 127 MPH (204 km/h) remained well offshore for its entire existence. As of the end of the 2005 North Atlantic hurricane season, Alberto (2000) was the second longest-lived tropical cyclone on record in the Atlantic basin, with a total distance traveled of 6,500 miles (10,500 km). Alberto’s marathon existence was topped only by 1966’s Hurricane Faith, which traveled some 7,500 miles (12,500 km). 

The first named tropical system of the 2006 North Atlantic hurricane season, Alberto, formed off the western coast of Cuba on June 10. A disorganized system with a weak convective center hampered by an unfavorable wind shear environment, Alberto remained a tropical depression (with a central pressure of 29.61 inches [1,003 mb]) for its entire existence in Cuban waters before recurving to the northeast and eventually making landfall near Adams Beach, Florida, as a powerful tropical storm. Like most tropical depressions and tropical storms, Alberto was a strenuous rainmaker, dropping significant amounts of precipitation on western Cuba and the southeastern U.S. While some Cuban reports indicated up to 16 inches (406 mm) of precipitation from Alberto, the system produced smaller counts during its passage over Florida and the mid-Atlantic states. Ruskin, Florida, received 6.71 inches (170 mm) of precipitation on June 13, while Raleigh, North Carolina, observed 7.16 inches (182 mm) on June 14, as the system was undergoing extratropical deepening. When the system trundled ashore on the Florida Panhandle on June 13, its central barometric pressure of 29.44 inches (997 mb) generated sustained wind speeds of 69 MPH (111 km/h).

Meteorologists attributed Alberto’s abrupt strengthening configuration prior to landfall to its interaction with the fueling waters of the loop current. Not surprisingly, Alberto’s constituent thunderstorms generated scores of tornadoes, including four in Florida. Although there were many reports of storm surge flooding in Florida and flash floods in North Carolina, Alberto’s passage was not considered particularly destructive. Two people indirectly lost their lives to Alberto, while damage estimates of $50 million were tallied. The identifier Alberto has been retained on the list of North Atlantic tropical cyclone names, and will be given to the first named tropical system of the 2012 season.

Air Mass

By definition, air masses are vast individual bodies of air within which the horizontal distribution of temperature and moisture is fairly uniform and stable. Covering expansive tracts of Earth’s surface in a single stretch, they are formed when the air remains stationary over a particular geographical location for an extended period of time, thus deriving a uniform temperature from that of the land or the sea below.

In practice, however, air masses are the purveyors of the world’s varied weather systems, including those unique elements required for tropical cyclone generation. Because the atmosphere is in constant motion, an air mass will not remain stationary indefinitely; in time, other air masses will move to displace it, creating in the convergence of different temperatures an atmospheric collision that yields the highs and lows associated with clement and stormy weather, respectively.

A front is the line where two air masses come together. The line where a warm air mass overtakes a cold air mass is a warm front; a cold air mass displacing a warm one is a cold front, and the situation where, because of similarities in temperature, neither air mass is able to overcome the other is a stationary front. Either way, the result is generally vicious weather, be it rain, snow, sleet, or thunderstorms.

Although hurricanes, typhoons, and cyclones are not extratropical cyclones and so do not contain the sort of frontal systems generally associated with stormy weather, they are nevertheless subject to the influence of air masses in motion. First, tropical cyclones begin as a revolving collection of thunderstorms over warm ocean waters—thunderstorms that are in themselves the direct result of a collision between air masses of contrasting temperature and moisture content.

Second, a tropical system develops as its central barometric pressure begins to fall and curving cloud bands start to gather around what will eventually become its eye. Rising air masses within the cyclonic system establish a crucial temperature difference between the storm’s core and its external environment. Following the laws of advection and convection, this temperature differential allows cooler air masses to descend toward the ocean’s surface and warmer air masses to ascend to what is known as an outflow layer. In time this relentless mechanical process determines the central pressure of the tropical cyclone and the intensity of its winds.

Furthermore, air masses often determine what course, or track, a particular hurricane will take across Earth’s surface. Because most tropical cyclones contain weak internal steering currents and so are not always able to choose where or when—if ever—they will make landfall, the presence of powerful external air masses becomes the primary means of locomotion for these storms. By deciding in what direction and at what speed a tropical cyclone will travel, air masses determine whether that system will make a potentially destructive landfall or will harmlessly pass out to sea.

Hurricane Agnes

Southern–Eastern United States, June 15–25, 1972 

A relatively weak Category 1 hurricane, its intense precipitation nevertheless initiated one of the most extensive flood emergencies in U.S. history. During a five-day sojourn up the eastern seaboard in June 1972, Agnes forced the displacement of more than 100,000 people, caused nearly $2 billion in flood damage, and claimed 134 lives in Florida, Georgia, Pennsylvania, New York, Virginia, and Maryland.

An early season tropical cyclone that originated off the northeast coast of Cuba on June 15, 1972, Agnes was just barely of hurricane strength when it first made landfall at Apalachicola, Florida, on June 19. Its 75-MPH (121-km/h) winds knocked out power lines, downed several trees, and caused an estimated $10 million in property damage; it otherwise spared Florida’s Panhandle the full promise of its later fury. Densely laden with more than 20 cubic miles of precipitation, Agnes slowly moved northeast, spawning no less than 17 tornadoes in central Georgia. Twelve people in Florida and Georgia were killed.

After briefly reintensifying off Georgia’s east coast, Agnes quickly swept across South and North Carolina and struck Virginia with hurricane-force gusts and torrential rains. In the state capital, Richmond, severe flooding caused the James River to crest at nearly 36 feet (12 m) above mean low water, breaking a record that had stood since 1771. Richmond’s reservoirs were polluted with silt and stormswept debris, while several multistory buildings in the business district were almost completely submerged. 

Close to 10,000 people were left homeless. Touring the area by helicopter, then President Richard M. Nixon quickly declared 63 of Virginia’s 96 counties federal disaster areas on June 26. Slowly progressing up the coast, Agnes then battered significant portions of eastern Maryland. Fierce rains and lingering winds forced more than 2,000 people to flee their homes and caused an estimated $50 million in damage. Extensive flash flooding completely immersed communication networks across the state, making it impossible to restore service for several weeks thereafter. Fifteen lives were lost. 

During the night of June 22, Agnes thudded into Pennsylvania. Swiftly rising flood waters washed away numerous highways and bridges and completely isolated the state capital of Harrisburg. The governor’s mansion was severely damaged when eight feet (3 m) of water burst through its lower story, sweeping it clean of its luxurious furnishings and historical artifacts. More than 100 miles (175 km) of the Erie-Lackawanna Railway’s main line was deluged, forcing the financially strapped railroad to file for bankruptcy protection on June 26. In Lock Haven, Pennsylvania, the Piper Aircraft Corporation suffered the near total loss of its principal manufacturing facility. The sprawling residential community of Wilkes-Barre was completely inundated when an astonishing 19 inches (48.3 cm) of rain forced the low-lying Susquehanna River to breach its 38-foot (13 m) dikes. Scientists estimated that by the morning of June 24, the Susquehanna’s thunderous flow was exceeding an astronomical one billion cubic feet of water per second.

Agnes further ravaged 14 counties in southern New York before blowing itself out over southern New England on June 25. The identifier Agnes has also been used in the western North Pacific Ocean for two systems that were of tropical storm intensity at landfall. Between September 25 and 28, 1965, Tropical Storm Agnes killed five people and caused several injuries as it passed ashore in Hong Kong. This large Chinese city was again affected by Severe Tropical Storm Agnes between July 24 and 30, 1978, in which three people were killed and 134 injured. The name Agnes has been retired from the rotating list of North Atlantic tropical cyclone names.

Advection

In the term’s strictest sense, advection is the transfer of any atmospheric property—be it heat, moisture, or motion—through horizontal movement. In a more general sense, advection refers to one of two meteorological processes (the other being convection) that creates wind.

In a hurricane, typhoon, or cyclone, advection results in the destructive winds that scour the surface of the land or sea—the flow of air that results when the cool, dense air that is descending toward Earth’s surface on one side of a convective cell is suddenly moved horizontally across the system’s bottom, only to be lifted up on the cell’s opposite side by rapidly rising or by convective currents of warm, light air.

This cyclical motion, which results from the uneven heating of the air by unequal surface temperatures, in turn serves to power the convective cell and will remain in continuous motion as long as the two contrasting surface temperatures persist. In tandem with the convective process, advection forms one of the principal mechanisms by which all atmospheric circulations, from global weather systems, to tropical cyclones, to localized supercell thunderstorms, are sustained.

Hurricane Adrian

Eastern North Pacifi c Ocean–Central America, May 15–23, 2005 

The first tropical cyclone of the 2005 eastern North Pacific Ocean hurricane season, and the first tropical cyclone to have made a recorded landfall on the western coast of Honduras, Hurricane Adrian destroyed roads, spawned flash floods and landslides, uprooted trees, downed power lines, and forced the evacuation of some 14,000 people as it trundled ashore near the Gulf of Fonseca on May 19, 2005.

A weak Category 1 hurricane with a central barometric pressure of 28.99 inches (982 mb) that had been downgraded to a tropical depression by the time it made landfall, Adrian nevertheless delivered sustained winds of 40 MPH (65 km/h) to the coastal town of Acajutla, located approximately 35 miles (55 km) west of the El Salvadoran capital of San Salvador. Adrian’s high winds churned across Central America at 12 MPH (19 km/h), killing an El Salvadoran military pilot whose aircraft crashed as it was being moved from Adrian’s path, while another two people in neighboring Guatemala perished in a mudslide caused by Adrian’s drenching rains. 

On May 20, Adrian disintegrated over Central America before its remnants reached the Caribbean Sea. On June 21, 1999, the western Mexican states of Coahuila and Colima were inundated by the outer rain bands associated with an earlier Hurricane Adrian. Formed near the Gulf of Tehuantepec, approximately 240 miles (386 km) southeast of Acapulco, Mexico, during the early morning hours of June 18, the system was upgraded to tropical storm intensity later the same day, and to hurricane status on June 20. Then located approximately 430 miles (692 km) south-southeast of Baja, California,

Adrian’s minimum central pressure of 28.73 inches (973 mb) produced sustained winds of 98 MPH (158 km/h) and heavy seas. Upon interacting with lower sea-surface temperatures and southeasterly wind shear, Adrian quickly weakened, returning to tropical storm status on June 21, and almost completely dissipating by the early evening hours on June 22. Although Adrian remained an offshore system for its entire lifespan, it was responsible for at least six deaths, including four people who drowned after being swept from a beach in Chiapas by a large wave generated by Tropical Depression Adrian on June 18; and another three people who died elsewhere in Mexico from riverbank flooding associated with Adrian’s large rainfalls. The name Adrian has been retained on the rotating naming lists for eastern North Pacific tropical cyclones.

Accumulated Cyclone Energy Index

Developed by the Tropical Prediction Center (TPC) and regularly employed by the National Oceanic and Atmospheric Administration (NOAA) and the National Hurricane Center (NHC) since the latter part of the 1990s, the Accumulated Cyclone Energy (ACE) index assists meteorologists and forecasters in analyzing, quantifying, and in some cases, predicting, the total seasonal activity of tropical cyclones within each of the Earth’s tropical cyclone generation zones. Determined through the use of mathematical formulas and models, the ACE index—which according to the NHC is a “wind energy index, defined as the sum of the squares of the maximum sustained surface wind speed (knots)”—is calculated every six hours for existing North Atlantic tropical systems of tropical storm intensity and higher. By including additional data such as the number of tropical storms and hurricanes, the number of major hurricanes, and geographical location, 

NOAA can use the ACE to categorize hurricane, typhoon, and cyclone seasons as being above-normal, near-normal, and below-normal. Since implementing the ACE Index, meteorologists at the NHC have (retroactively) applied the technique to North Atlantic tropical cyclones dating from 1950–2005, and used the ACE Index to determine a base period from 1951–2000. These studies indicate that the median annual index for this base period was 87.5.

In terms of definitional clarity, an above-normal season generally possesses an ACE Index value above 103, or 117 percent of the median, and includes either 10 tropical storms, six hurricanes, or two major hurricanes. A near-normal season carries an ACE Index value of between 66 and 103, and is generally representative of 75 percent to 117 percent of the median. Additionally, a near-normal season is characterized by having less than the long-term average number of tropical storms, hurricanes, or major hurricanes. And a below-normal season has an ACE Index value of 65 and below, which generally translates to 75 percent of the median as determined by the base period data.

According to records maintained by NOAA, the top five North Atlantic tropical cyclone seasons as determined by the ACE Index were: 2005, 1950, 1995, 2004, and 1961. In the case of the extraordinarily active 2005 North Atlantic hurricane season, an ACE Index of 248 was derived. In addition to the severity of the storms produced during that season, there were a total of 27 named tropical systems, with seven of them reaching major hurricane status. Although the 1950 season produced less than half the number of named storms observed during the 2005 season (a total of 13 tropical systems), it generated an above-average number of major hurricanes (eight), which gave it an ACE Index value of 243.

Cape Verde

CAPE VERDE IS a volcanically produced archipelago, consisting of 10 major islands and five islets in the ATLANTIC OCEAN, 285 mi (460 km) off the coast of SENEGAL in Africa. Settled by the Portuguese sometime between 1455 to 1461, the uninhabited and resourcepoor Cape Verdes offered an early lesson in what today’s marketing gurus refer to as: “location, location, location.” The craggy islands, with their hot, dry climate, were of little intrinsic value. Rain came sporadically, but sometimes in torrents, ruining whatever crops might otherwise grow.

Trade winds swept early sail-powered vessels to Cape Verde, and PORTUGAL capitalized, vigorously, on the islands’ location. Descending from north to south, the AZORES, Madeiras, and Cape Verde formed strategically positioned stepping-stones to and from the Atlantic for Portugal. Their natural and manufactured resources were collectively leveraged for the Crown, and also offered an African trade axis with its own cultural and economic attributes.

Portugal carefully planned its colonial economies. Goats, which could survive virtually any terrain, were brought to Cape Verde even before settlers. A preservative and dietary supplement for long transoceanic voyages, salt proved to be the only redeemable natural resource. The Portuguese also envisioned Cape Verde as a trade outlet for their naval stores, but proximity to the African coast rendered slave-trading the largest commercial activity, peaking in the first half of the 17th century and ending in the early 19th, when most of the world outlawed it. In order to settle the islands and bolster their profitability, the Portuguese crown initially extended trade privileges to private firms and issued land grants with the hope of seeding plantationstyle agriculture. (Farming largely failed. Ironically, some of the best-growing crops, notably beans and squashes, were New World imports.)

Less privileged individuals arrived at Cape Verde, too: Former prisoners brought at government behest for their labor; Iberian Jews fleeing the Inquisition; independent adventurers of truly diverse nationalities; slaves and freed slaves (often liberated during times of extreme drought/famine when even wealthy Cape Verdeans could not provide for them); and their wellmixed progeny.

The early elite profited from government-granted status, but others were forbidden to trade with foreign countries and limited in what they could exchange (no guns to Africa, for example). They frequently flouted colonial dictates and embarked on their own trade, sometimes through smuggling. Generally, they learned to navigate—both commercially and culturally—the African coast with its myriad tribal leaderships. Three major trade classes subsequently emerged: tangomaus, originally black African traders who adapted to Portuguese culture; lancados, white Portuguese who ventured from Cape Verde to Africa; and grumetes, black or mixed-race servants who worked the boats and hauled cargo. With the end of slave trading, Cape Verde returned to provisioning. Faster, more efficient steam ships plied the seas, and newly discovered coal and a good harbor at Mindelo (San Vicente Island) fueled the economy.

Combined with poor conditions at home, increasing cosmopolitanism for the first time encouraged a major exodus: Seafarers from the island of Brava joined western-bound whaling crews and, subsequently settled in RHODE ISLAND, CALIFORNIA, and primarily MASSACHUSETTS. Cape Verde achieved recognition as a geocultural “broker” in the 20th century. In addition to building transportation facilities, Portugal established the islands as an educational center for its African colonies, with a seminary and secondary school. But the pervasive anticolonial movement sweeping the continent similarly inspired Cape Verdeans toward independence in 1975. All told, the islands’ geographic position yielded a maritime economy descended from the Age of Exploration, and a unique Afro-Portuguese Crioulo (creole) culture that became better defined with the dissolution of colonialism.

Canyon

A CANYON IS A deep, narrow passage cut through the surface of the Earth with steep cliffs on both sides. Sometimes called a gorge or ravine, canyons are often formed in mountainous, arid, or semiarid regions where riparian EROSION is much greater than erosion from general weathering. They range in size from an arroyo, or ditch, to the GRAND CANYON, with its depth of more than a mile. Canyons can be found all over the world, at the bottom of the ocean, and even on other planets. 

The word canyon is thought to originate in the Spanish cañon, which means “tube” (from the Latin canna, a reed). This root is descriptively accurate because canyons are frequently in the shape of a tube, having been carved by the constant flow of water between surrounding walls.

Canyons are formed and deepened by erosion from moving water and may be widened by landslides. A number of canyons were carved out of the Earth by massive glaciers, some more than a mile thick, which took millions of years to cut their way through solid stone. As the surface of the Earth has been shaped by climate over eons, cycles of ice age followed by thaw have occurred, and much land that is desert today was under water at some time, submerged below ancient seas.

These ancient seas deposited sediments, which settled in layers, and nowhere are those layers more evident than in the walls of a canyon. As snows melt and collect in rivers, the force of water slowly carves channels through these layers, exposing the history of the land in a sedimentary cross-section of Earth. These exposed layers offer an excellent living laboratory for scientists to study the geological changes in the Earth’s crust. For example, at the Grand Canyon’s rim, the Earth is only 250 million years old in places; on the floor of the canyon, the most ancient layers are thought to be up to 1,200 million years old.

As rivers erode deep into the canyon floor, they become entrenched and cannot easily alter their course, thereby deepening themselves further, faster. These rivers become deeper and canyon walls become higher and higher. The Grand Canyon slices through the Earth’s crust for 217 mi (347 km) miles from beginning to end. It averages 10 mi (16 km) across—almost 20 mi (32 km) at some spots—and over 1 mi (1.6 km) deep. The Snake River and its Hells Canyon are another example of river entrenchment; while such canyons are massive, they are not the biggest on Earth. That honor goes to the canyons that form on the ocean floor, called submarine canyons.

Submarine canyons, forged by some of the same forces as canyons above sea level, dwarf the Grand Canyon in magnitude. The force of rivers emptying into the ocean, massive underwater landslides, and mudflows combine to carve out submarine canyons. One of the largest of these canyons, the Great Bahamas Canyon or Trench, measures 14,000 ft (4,575 m) from rim to floor; that’s twice as deep as the Grand Canyon. As impressive as these numbers are, the biggest canyons in the solar system are not found on Earth. On the planet Mars, the Valles Marineris canyon system spans over 2,500 mi (4,000 km) from end to end—about the distance from New York to San Francisco— and has a depth of up to 6.25 mi (10 km). Scientists are interested in canyons on Mars because they may indicate the presence of water at some time in the planet’s history, and the presence of water on Mars—confirmed by NASA’s 2004 robotic-lander mission to the Red Planet—indicates the possible presence of life.

Canyons are important for many reasons. Their striking beauty and the diverse flora and fauna that flourish there enrich the landscape and the lives of the people who experience them. They can provide information about climate changes in the past and may help predict climate changes in the future. They are also important to archaeologists because of the artwork and fossils found on canyon walls, and the cliff dwellings built in the steep walls of some canyons can teach us about ancient cultures.

Canary Islands

THE CANARY ISLANDS lie just 93 mi (150 km) off the northwest coast of Africa in the ATLANTIC OCEAN but have been politically and culturally attached to SPAIN, 830 mi (1,350 km) to the northeast, since the 14th century. Today the seven islands, an autonomous region of Spain, are among the most popular holiday destinations for tourists from northern Europe. The islands’ proximity to Africa is apparent in their climate, an extension of the deserts of the SAHARA. Some areas are semiarid, with abundant cacti and maspalomas (large sand dunes), while higher elevations host laurel and pine forests, with subtropical and tropical plants in the valleys in between. The islands are volcanic in origin and reflect this in their steep inclines and rugged cliffs. They vary in age and volcanic activity, from the oldest, Fuertaventura and Lanzarote in the east, to the most recently formed La Palma and El Hierro, furthest west in the chain. La Palma has seven volcanoes that have erupted since the 15th century, most recently Teneguía, in 1971. It also has a large collapsed caldera in the center of the island (Taburiente), with a rim averaging 6,600 ft (2,000 m) in height and an astronomical observatory.

Between these extremes of old and new islands at the eastern and western ends of the chain, lie the largest and most populated of the Canary Islands, Tenerife and Gran Canaria. Most of the beach resorts and nightclubs are on these two islands, but they too have their share of scenic ravines and mountain peaks—Pico del Teide is the highest point not only in the Canary Islands, but in all of Spain. Lastly, the small island of La Gomera, where isolation has best preserved the indigenous culture of the Guanches people, including their distinctive pottery made without a wheel, and the famous whistling language, Silbo, used by shepherds to communicate between sharp valleys and cliffs for centuries.

The Guanches are believed to be immigrants from North Africa, but legends name them as the only survivors of the lost continent of Atlantis. The ancient Greeks knew of the islands, as the last known land after the Pillars of Hercules (the Straits of Gibraltar). They were known as “the Happy Isles” before cartographers started calling them the Canaries—possibly due to the large hunting dogs (canis in Latin), still bred on the islands today (called verdinos or bardinos). But little was known about the islands until they were visited by a Genoese explorer, Lancellotto Malocello in 1312 (giving his name to Lanzarote). Ancient mariners drew the first meridian at El Hierro, marking the western edge of the world (today this is the west 18th).

Spanish monarchs established control over all of the islands between 1402 and 1504 and resisted repeated attempts by the Dutch and English to take the islands. The islands were coveted as the important last stop before setting off to cross the Atlantic, starting with Columbus himself, who last saw land at La Gomera on September 6, 1492. The islands formed two provinces, Santa Cruz de Tenerife and Las Palmas, until the reorganization of Spain into regions in 1984, which made the Canaries one region, with relative internal autonomy. Less than 10 percent of the gross domestic product is generated by agriculture, mostly bananas, especially on Tenerife, but also figs, grapes, and almonds in areas with a more Mediterranean climate.

Rather, it is tourism—over four million visitors a year come to Tenerife alone—that contributes most to the local economy and provides residents with a per capita income higher than that of mainland Spain.