Hurricanes: Background information when reading Zeitoun

Hurricanes

This article relates to Zeitoun

The term "hurricane" is believed to originate with the Carib people of the West Indies (after whom the Caribbean was named). Historians believe that the Carib word huracan was probably derived from the Mayan storm god, Hunraken or the K'iche god of thunder and lightning, Hurakan. K'iche (in Spanish Quiché) is a part of the Mayan language family spoken by many people in the central highlands of Guatemala.

Hurricanes form when moisture from warm ocean water (at least 80^oF/27^oC) combines with warm air at the ocean surface.   The developing storm is then hit by a strong surface wind that spirals the air inward.  Bands of thunderstorms form over this storm which allows the air to warm further and rise higher into the atmosphere.  Lighter winds at higher levels allow the structure to remain intact and grow.  Because of the sea temperatures needed to form a hurricane they occur almost exclusively in the tropics, but cannot form within 300 miles of the equator due to insufficient Coriolis Force – the force that causes hurricanes to spin clockwise in the southern hemisphere, and counter-clockwise in the northern hemisphere.

For several hundred years hurricanes in the West Indies were named after the saint's day on which they occurred; then meteorologists moved to designating them by their latitude-longitude, which proved cumbersome. During WWII, the USA took to using women's names, a practise which continued, broadly speaking, up until 1978 when a six year rotating list of male and female names was developed, with separate lists for Atlantic and Pacific storms. Whenever there is a powerful hurricane which makes landfall and causes death and damages, its name is retired from the list to avoid future confusion. There are no hurricanes starting with the letters Q, U, X, Y, and Z due to the lack of available names.

A storm goes through various stages before it's considered a hurricane.  It begins life as a tropical disturbance, with showers and thunderstorms but little or no circulation.  A tropical depression forms when the storm begins to rotate and winds pick up to 25 to 38 mph.  A tropical storm has winds of 39-73 mph, graduating to hurricane status at 74 mph. 

A hurricane is comprised of multiple parts.  The eye is a small area of calm in the center of the storm, perhaps 20-30 feet in diameter.  Surrounding the eye is the eyewall, a ring of heavy showers and thunderstorms, this is where the most severe weather occurs. Above the entire storm is a rotating circular mass of clouds called the dense cirrus overcast. The areas of rain and thunderstorms beyond the eye wall are known as rain bands. Storm surges, also known as storm tides, are caused mainly by high winds pushing on the ocean's surface and are responsible for about 90% of hurricane deaths.

Scientists estimate that in a single day a hurricane can release the amount of energy necessary to satisfy the electrical needs of the entire United States for about six months!

Filed under Medicine, Science and Tech

This article relates to Zeitoun. It first ran in the June 9, 2010 issue of BookBrowse Recommends.