A hurricane is a tropical storm that has winds of over 74mph. In the Caribbean Indian language, "hurricane" means "evil spirit and big wind." Hurricanes need three things to form: moist air, warm water, and converging winds. A hurricane forms when winds meet over warm water (at least 80 degrees F) and push each other in a turning pattern. The majority of Atlantic hurricanes begin on the West Coast of Africa and are pushed west towards the Americas.
Most hurricanes begin near the equator. The leftward-circulating winds from the south meet right-circulating winds from the north due to the Coriolis effect (spin of the earth).
These winds pull warm air from the surface of the water and push it upwards, creating a funnel. The center of the funnel is the eye of the hurricane, which is surprisingly, very calm. The Eye Wall, however, is where the wind is compressed into a relatively tight space and the spin of the cloud formations is the most turbulent. The clouds are formed from the moisture pulled up from the surface of the water as the air rises from it.
From the center of the hurricane's eye to the Eye Wall is calm. As you move outward from the walls of the eye, however, the hurricane gets calmer as the area the winds are circulating in gets larger. The circulating cloud formations around the Eye are dark because they are the rain bands where rain falls, though most of this evaporates back into the storm before reaching the surface.
The heat of the water is the fuel source for the feeds on itself – spinning left if headed south and right if going north. As hurricanes recirculate their energy, they have a exponential growth, growing in size. Hurricanes usually lose most of their energy upon landfall or when entering cooler waters because a crucial element is warm water.
Many storms, for instance, will become hurricanes on the weather map only to move into a micro climate of cooler water (perhaps a current of cooler water originating at the pole) and then lose their force, dying off.
A hurricane's life span is usually measured in a few short days. A low pressure zone in the tropics will be called a tropical depression, which is the beginning of a hurricane. As winds pick up and feed on one another, the storm might begin moving north or south, increasing in size and intensity. This is a tropical storm, or baby hurricane.
Eventually, if conditions are right, the tropical storm will continue moving north or southwards|south or north] and will reach wind speeds of over 74mph. Only then is it a hurricane. Generally, the less spread out a hurricane is, the more potential damage it will do on landfall. Imagine a ball thrown at your nose, for example. The bigger the ball is, the more spread out the impact area will be and the less damage your nose will incur. A small ball like a baseball or golf ball, hitting your nose directly, will hurt more than a larger one, like a beach ball.
Every year, on average, about 100 tropical storms develop. About half of those become hurricanes, but only about 5 to 10 percent of those make landfall in an inhabited area. The majority of hurricanes never make it to shore.
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