Monday, September 1, 2008

Hurricanes : The Engines of Distruction

Hurricanes are giant, spiraling tropical storms that can pack wind speeds of over 160miles (257 kilometers) an hour and unleash more than 2.4 trillion gallons (9 trillion liters) of rain a day. These same tropical storms are known as cyclones in the northern Indian Ocean and Bay of Bengal, and as typhoons in the western Pacific Ocean.

Hurricanes and typhoons ARE tropical cyclones;they are regional names for the same meteorological event.

The Atlantic Ocean’s hurricane season peaks from mid-August to late October and averages five to six hurricanes per year.

Hurricanes begin as tropical disturbances in warm ocean waters with surface temperatures of at least 80 degrees Fahrenheit (26.5 degrees Celsius). These low pressure systems are fed by energy from the warm seas. If a storm achieves wind speeds of 38 miles (61 kilometers) an hour, it becomes known as a tropical depression. A tropical depression becomes a tropical storm, and is given a name, when its sustained wind speeds top 39 miles (63 kilometers) an hour. When a storm’s sustained wind speeds reach 74 miles (119 kilometers) an hour it becomes a hurricane and earns a category rating of 1 to 5 on the Saffir-Simpson scale.

Hurricanes are enormous heat engines that generate energy on a staggering scale. They draw heat from warm, moist ocean air and release it through condensation of water vapor in thunderstorms.

Hurricanes spin around a low-pressure center known as the “eye.” Sinking air makes this 20- to 30-mile-wide (32- to 48-kilometer-wide) area notoriously calm. But the eye is surrounded by a circular “eye wall” that hosts the storm’s strongest winds and rain.

These storms bring destruction ashore in many different ways. When a hurricane makes landfall it often produces a devastating storm surge that can reach 20 feet (6 meters) high and extend nearly 100 miles (161 kilometers). Ninety percent of all hurricane deaths result from storm surges.

A hurricane’s high winds are also destructive and may spawn tornadoes. Torrential rains cause further damage by spawning floods and landslides, which may occur many miles inland.

The best defense against a hurricane is an accurate forecast that gives people time to get out of its way.

Hurricane Gustav is the seventh tropical cyclone, third hurricane and second major hurricane of the 2008 Atlantic hurricane season. It formed on the morning of August 25, 2008 about 260 miles (420 km) southeast of Port-au-Prince, Haiti, and rapidly strengthened into a tropical storm that afternoon and into a hurricane early on August 26. Later that day it made landfall near the Haitian town of Jacmel. As of August 31, 88 deaths have been attributed to Gustav in the Caribbean.

On September 1 at 9:30 a.m CDT (1430 UTC) the center of Gustav made landfall in the United States along the Louisiana coast near Cocodrie as a category 2 hurricane.