What is a hurricane and how is it formed?

1 Answer
Jul 10, 2015

A hurricane is a very intense tropical low pressure system with wind speeds above 63 kts.


Water vapor is lower pressure than dry air. As a low pressure moves over the warm ocean, particularly over and long stretch of warm water (called the fetch), evaporating water is going to enter the atmosphere and make that low get stronger (deepen). The warm wet air will rise (as warm air does) and it will get cooler as it goes up (at the lapse rate). Eventually this air will be so cold that it cannot hold all off the water as vapor and there is condensation. This creates cloud.

Now as the water goes from gas to liquid it releases energy (molecules in a gaseous state have more energy that those in the liquid state). This energy heats the air, which causes the already rising air to get warmer and keep rising. This in turn causes the air to cool and the water to condense, and this cycle feeds itself until the air rises to the point that it is no longer warmer than the surrounding air.

If the wind through the various heights of the atmosphere are relatively equal, we end up with a situation 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. With water vapor being injected into the system from the warm ocean and allowed to freely rise in the column because there is no heights were it is removed from the developing storm by higher winds, the storm can build to much much bigger dimensions.

By the time the process is done, depending on how long the warm water fetch is and how warm the water is, you can end up with a storm that has more energy in it than 10,000 nuclear bombs. Try flying your kite in that!