Hurricanes are considered to be the most devastating events to ever occur.  They are born over water and driven by solar energy stored in the ocean.  Hurricanes, also called tropical cyclones, can travel for weeks across the ocean, blasting islands and coastlines with fierce winds, swollen seas, and torrential rains.  Hurricanes can also remake land by tearing up barrier islands and dunes while depositing sand on other beaches.  However, as soon as a hurricane reaches land, it begins to lose its power.  Hurricanes can also remake history.  The Galveston, Texas hurricane of 1900, killed over 9,000 people and practically erased the city, helping to convert the inland city of Houston into a petrochemical giant. 

Weather satellites are now able to track hurricanes to their sources.  For example, Atlantic hurricanes originate off the coast of West Africa, where “tropical disturbances” form in low-pressure zones.  A disturbance may intensify into a tropical depression surrounded by a high-pressure zone that helps to contain the storm.  This storm is centered on a column of rising air.  Winds are moderate between 21 to 35 miles per hour.  Once the winds exceed 35 miles per hour, the systems, called a tropical storm, gets an alphabetical name.  The storm has the circular structure of a hurricane, although it may not become one.  Powered by solar heat that was stored in the ocean and then transferred into the warm and moist air, the tropical storm becomes a hurricane once winds exceed 74 miles per hour. 

Hurricanes feed on themselves to gain strength. In their energy flow, hurricanes resemble large thunderstorms.  Unlike thunderstorms that can start over land or water, hurricanes only start over water.  Hurricanes also last much longer, carry greater energy, and cause much greater destruction.  Tropical cyclones are powered by heat engines, which are “machines” that use heat to do their work.  The hurricane sucks in the warm and humid air from the lower atmosphere.  The air then rises and condenses, releasing water vapor and the amazing amount of heat energy that the moisture absorbed as it evaporated from the ocean.  Finally, the storm exhausts the expanded air into the upper atmosphere.  The released heat drives hurricane winds and powers the upward convection in the storm.  The rising air creates a low-pressure area near the ocean that draws in more energy-laden air, which feeds the continuing storm.

Hurricane winds whirl around the bizarrely calm “eye,” which is a circular region with little wind, no rain, and a blue sky.  A circular “eye wall” of thunderstorm type clouds and the fiercest of winds surround the placid eye.  When Hurricane Camille tore up the U.S. Gulf Coast in 1968, winds in the eye wall reached over 200 miles per hour.  High winds combined with extremely low atmospheric pressure near the eye, causes a catastrophic rise in sea level called a storm surge.  This destructive mound of water is topped with wind whipped waves, can hoist the surface 20 feed above the average sea level which can cause biblical scale flooding along coastlines. 

Although storm surges are the most dangerous element of these storms, water causes another grand problem.  All of that condensing moisture eventually falls as torrential rain.  Although hurricane winds slow as they move inland, the rains can still be drenching.  Hurricanes will come and they will go, but the overall trend is periodic lulls followed by a series of treacherous years.  Hurricanes may not be getting more intense, but the damage is increasing due to development and torrid population growth in the prime hurricane country, which in the United States includes the Carolinas, Florida, and the Gulf Coast.

 

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