Do Hurricanes Form Over Water?
Hurricanes do form over water. Hurricanes can only form over very warm, humid water, such as that found in the Atlantic and eastern Pacific Oceans near the equator. Hurricanes require water of at least 80 degrees Fahrenheit as a kind of fuel, both to form and to continue to move and gain power.
How Do Hurricanes Form?
A hurricane forms when warm ocean water heats the air above it and causes the air to rise. This creates a pocket of low pressure over the water. Air from the surrounding atmosphere rushes into the area of low pressure, creating wind. As the warm, moist air rises and cools, it condenses into clouds. The continuous evaporation of warm water and cycling of air as it rises and cools causes the storm to begin to spin and move.
Why Do Hurricanes Form Only Over Water?
A hurricane requires warm water above 80 degrees Fahrenheit to form. They generally form in tropical areas because the water needs to maintain this temperature for at least 200 feet to continue to fuel the hurricane as it pulls water into the system. If cooler water is pulled into the system, the storm will begin to weaken.
Why Do Hurricanes Weaken Over Land?
Once a hurricane encounters land, it typically slows and loses power for several reasons. Primarily, the hurricane loses its latent heat source, high temperatures, and dew points over land. Land, especially land under heavy clouds, tends to be cooler than the ocean and absorbs water, making it evaporate more slowly. To a lesser extent, the friction of the land surface may inhibit wind speed and weaken the Coriolis Effect, but at the same time, the wind gusts may increase as the storm meets with more turbulence bringing faster gusts of winds in short bursts down to the surface.
Resources
NASA
How Do Hurricanes Form?
http://spaceplace.nasa.gov/hurricanes/
USA Today
Why Hurricanes Hit in Summer, Early Fall
http://usatoday30.usatoday.com/weather/whur5.htm
Department of Geosciences San Francisco State University
Hurricane Questions
http://tornado.sfsu.edu/geosciences/classes/m302/hurricanequestions.html]
Atlantic Oceanographic & Meteorological Laboratory
Doesn’t the Friction Over Land Kill Cyclones?
http://www.aoml.noaa.gov/hrd/tcfaq/C2.html
