What is a hurricane and how is it formed?

The pressure of water vapor is lower than that of dry air. When a low pressure system passes over a warm ocean, especially over a long stretch of warm water known as the fetch, evaporating water will enter the atmosphere, strengthening the low pressure and causing it to deepen. Warm, wet air will rise as it always does, but as it rises, it will get colder (at the lapse rate) until it becomes too cold to hold all of the water vapor as vapor, which will lead to condensation and the formation of clouds.

Now that the water is changing from a gas to a liquid, it releases energy (because gaseous molecules have more energy than liquid ones), which heats the air and causes it to rise further. This causes the air to cool and condense, and the cycle repeats itself until the air rises to the point where it is no longer warmer than the surrounding air.

With water vapor being injected into the system from the warm ocean and allowed to freely rise in the column because there are no heights where it is removed from the developing storm by higher winds, the storm can build to much much bigger dimensions if the wind through the various heights of the atmosphere is relatively equal. This means that the developing storm is able to continue developing at all levels of the atmosphere because it is not getting "blown" over by higher winds aloft.

You could wind up with a storm that has more energy in it than 10,000 nuclear bombs by the time the process is complete, depending on how long the warm water fetch is and how warm the water is. Try flying your kite in that!

A hurricane is a powerful tropical storm with a well-defined circulation pattern, sustained winds of at least 74 mph (119 km/h), and organized thunderstorms. They form over warm ocean waters when sea surface temperatures are at least 26.5°C (80°F), and the atmosphere is conducive to convection and low wind shear.