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DISCOVERY
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Earth is a complex and dynamic system. There is no process or phenomenon on Earth that occurs in isolation from other elements of the system. Land, air, water, and life interact to produce any phenomenon. Hurricanes are good examples of the complexity of these interactions. The energy that drives a hurricane comes from the sun. Solar energy is absorbed by the dark ocean surface. Radiation from the warm ocean surface warms the air above. As the ocean warms, the air above it grows warmer and warmer--an interaction between the air and water. Warmed air is less dense that cooler air. That makes it rise. When air rises high enough it cools and moisture in the air condenses and form clouds. When enough moisture has collected in the clouds, rain begins to fall. The warmer the ocean, the faster the air rises. Rising air lowers the barometric pressure. Wind begins to blow and a hurricane is born. Once it has formed, the path and strength of a hurricane are determined by interactions. Interactions that affect the path and strength of a hurricane: Water : Storm &emdash; When a hurricane passes over warm water it grows in strength. When it passes over cooler water its winds slow. Storm : Water &emdash; Low pressure in the center of a hurricane causes the surface of the ocean to rise several meters. This increased height causes a storm surge Air : Storm &emdash; High- and Low-pressure air masses can affect the path that a hurricane follows. In the Northern Hemisphere wind travels clockwise around a High and counter-clockwise around a Low. (It goes the other way in the Southern Hemisphere.) As a hurricane approaches one of these air masses, its path can be altered by wind direction. Storm : Land &emdash; The winds and rain of a hurricane can change the surface of the land through wind and rain erosion. Land : Storm &emdash; When a hurricane passes over the land the friction slows its winds. Since it is the warm water surface that drives a hurricane, passage over land cuts off the power from a hurricane. Storm : Life &emdash; A hurricane can destroy life. Plants and animals are killed when a hurricane passes over. Life : Storm &emdash; Living things can actually slow the winds within a hurricane. Can you think of how this can be? Right... trees cause friction with the winds of a hurricane that actually slow the winds. |