As the air rises, it leaves a low pressure area that draws in more energy-laden air, continuing the process. The complex structure of a hurricane draws in warm, moist air down low and exhausts cooler, drier air up top. The storm naturally converts the vast quantity of latent heat in warm, moist air into kinetic energy. Powered by solar heat that was transferred to the ocean and then the warm, moist air, the tropical storm may become a hurricane if its winds exceed 74 miles per hour. Although hurricanes and tornadoes are both powerful, rotating storms, there are big differences.
Hurricanes only start over water, while tornadoes can start over water or land.
And hurricanes last much longer and carry far greater energy than tornadoes. Hurricane winds whirl around a calm, circular, often blue-sky region with little wind and no rain called the eye. When Hurricane Camille slammed into the Gulf Coast in 1968, winds in the eyewall reached 200 miles per hour. Gargantuan winds, combined with extremely low atmospheric pressure near the eye, cause a catastrophic rise in sea level called a storm surge. This destructive mound of water, covered with waves whipped by the furious winds, can hoist the surface by 20 feet above average sea level, causing biblical-scale floods along coastlines.