The word hurricane is the English translation for what ancient Caribbean Indians called the evil spirits they believed responsible for storms with large winds, in the Caribbean Sea. Nevertheless, the word hurricane now includes those that develop in the Caribbean, Atlantic and Pacific Oceans and the Gulf of Mexico.
Hurricanes begin as tropical cyclones, which is an all-encompassing phrase referring to a low-pressure pattern, says Weather.Com. Westerly winds blow in tropical waves of low-pressure about once a week, and a portion of them form tropical depressions, and progress to hurricanes.
How Hurricanes Form
As tropical cyclones develop, major thunderstorms form and air pressure drops. The low pressure pulls warm, moist air from the surface of the ocean, into the cyclone. The winds in the cyclone turn counterclockwise if it’s in the Northern Hemisphere, or clockwise if it’s in the Southern Hemisphere. The eye of the hurricane is its center, around which the wall of wind blows. It appears calm, and is the weakest part of the hurricane. The eye forms, when the wall of winds surrounding the hurricane reaches hurricane force of 73mph.
A simple explanation is to picture a hurricane as a big heat engine, and its fuel is warm, moist air from the ocean. Thunderstorms form, and the winds spinning around the center of the hurricane draws moisture from ocean into the winds. The moisture spinning in the wind, creates more heat that is fuel for the hurricane therefore, it increases in power. The power increases until it reaches land where there is no warm moisture to feed it, and is slowly loses power. A hurricane then, is a hollow core, the eye, with winds of at least 73mph swirling around it.
Stages of a Hurricane
Hurricanes begin as tropical disturbances, which are systems of clouds, rain and thunderstorms that remain intact for 24 hours. After 24 hours, these disturbances now are tropical depressions with winds blowing at least 38mph around a center of low pressure. If winds increase in velocity from 39 to 73 mph, the depression becomes a tropical storm. The tropical storm becomes a hurricane, when the wind blows more than 73 mph.
The possible damage a hurricane is capable of doing is put into a category from 1 to 5, with 5 being the most dangerous. The category of a hurricane depends on wind speed, and barometric pressure.
The Weather Channel: Hurricanes and Tropical Storms: weather.com