Why Does A Hurricane Weaken When It Moves Toward Land?
Why do hurricanes lose power once they reach land?
Because storms draw their power and strength from the water they form over. In shallow waters like the Gulf of Mexico, the surface temperatures tend to be warmer, which can cause the growth of superstorms like Hurricanes Katrina and Rita. We all remember the amazing amounts of damage these two storms were able to do, yet once they made landfall, they rapidly lost strength and fizzled out.
Think of the large bodies of water, especially warm water, as food for hurricanes - more evaporation, more precipitation, and more wind speed. Once on land there is nothing for them to continue to draw energy from, and the storm moves north and loses strength.
Hurricanes use the warm and moist water of the ocean as fuel. The warm air rises up and away from the surface leaving less near the surface (low air pressure). This is why they have more energy over the ocean than they do over land. They may be incredibly powerful over land but eventually they begin to die out. The warm ocean water is a necessity for the storm to grow.
Another reason that hurricanes lose power when they move over land is because of friction.
In addition, if the hurricane experiences vertical wind shear it will also lose its power.
Hurricanes begin when there is a low pressure system in warm tropical oceans. The right combination of barometric pressure, wind circulation and thunderstorms creates strong winds, heavy rain, large waves and flooding. This disturbance is then classified as a tropical depression, tropical storm, or hurricane. Classification is based on how fast/strong the maximum sustained winds are. Hurricanes have maximum sustained winds of 74 mph or higher and a well-defined center of circulation.
Most hurricanes lose intensity rapidly after making landfall because landforms, buildings and other obstacles "slow it down" by removing the things it loves (low pressures, open spaces, light winds and warm water. So, the storm has less chance to regenerate on land. As a result it loses power and energy. Unfortunately, the power and energy are often transformed into excessive thunderstorms resulting in flooding and the damage it causes.
Hurricanes are powerful whirling storms with whirl diameter in the range of 320 to 489 kilometers. The wind at their center blow at speed of 120 kilometres per hour or more. Hurricanes develop over seas and oceans n tropical regions in either the North Atlantic Ocean or eastern North Pacific Ocean by action of easterly winds called trade winds. Similar storm in the western Pacific Ocean is called a typhoon, and one in the Indian Ocean is called a cyclone.
Travelling at a speed of about 20 kilometers per hour initially. They become larger and stronger as they travel. Then they turn from the equator and pick up speed and usually turn east after they reach temperate latitudes.
Many hurricanes end up as weak storm centres over cool oceans.Also hurricanes weaken as they move over land.. This happens because hurricanes need warm sea to supply energy by evaporation. Also friction caused by the rougher land surface also slows down the winds.