Hurricanes

Hurricane is the name for an intense and dangerous type of cyclonic storm known through most of the tropical regions of Earth. In the Atlantic Ocean and in the Pacific Ocean east of the International Dateline the storm is called a hurricane. In the Pacific Ocean west of the International Dateline it is known by the name typhoon although there are local appellations such as baguio (Philippines) and willy-willy (Australia). The storm is known as a tropical cyclone or, simply, cyclone in the Indian Ocean and the western South Pacific Ocean. The name appears to originate from the Spanish spelling of a word “huracan” used by peoples of the Caribbean basin to denote a “god of evil” but is alternatively translated as “big wind.”

Hurricanes usually start as tropical waves that are mild disturbances in the trade wind of the tropical latitudes. These tropical waves pass from east to west at speed averaging around 20 km/hr with wavelengths somewhat over 2,000 km. The waves are common, with a hundred or so passing over the North Atlantic during its hurricane season. They are areas of disturbed weather containing rain and thundershowers and pass over a location in 3 to 4 days. A few of these storms develop closed isobars whence they are named tropical depressions. When wind speeds exceed 17 m/s they become tropical storms and when the wind exceeds 34 m/s they become hurricanes.

Hurricanes can exist for days at a time. Some hurricanes have lasted for upward of a month, but hurricane force winds usually inhabit the disturbance for an average of a few days. Hurricanes weaken as they pass over cool water or over land or encounter strong, shearing winds at high altitude; any of these conditions disrupts the latent heat supply on which the hurricane feeds. The strengths of tropical disturbances are rated on the Saffir-Simpson scale. The scale ranges from category 1 through category 5. T