Q: Why do hurricanes occur where they do?
— Kylan Pratsch, 8, Crestwood Elementary School, Madison
A: Hurricanes form near places like Florida because hurricanes need some critical components to develop. They need a lot of water, and they also form near the tropics because they need a lot of sunlight.
The sun heats the water, and that water starts evaporating and cools into clouds. As the water evaporates, a hurricane will get its energy from the clouds.
A hurricane also needs very low vertical wind shear. That means the wind at the surface needs to be about the same speed as the wind near the upper parts of the atmosphere. If the wind is changing a lot with elevation and getting stronger as it gets higher in the atmosphere, hurricanes can’t form because they end up getting sheared. Wind will blow the top off the clouds, and a hurricane can’t develop and get its spin.
This year, hurricanes hit the states of Florida and Texas, as well as Puerto Rico, a U.S. territory. The western Pacific Ocean near Japan and China gets a lot of hurricanes as well, though they’re referred to as tropical cyclones.
Tropical cyclones that form in the Southern Hemisphere turn clockwise, while those that form in the Northern Hemisphere turn counter-clockwise.
While Wisconsin doesn’t get hurricanes, it can still feel the effects of hurricanes. Once a hurricane makes landfall, like Hurricane Irma did in Florida, the effects can be far-reaching and can extend up the East Coast.
Some hurricanes, especially the ones that don’t hit land, will eventually undergo something called extratropical transition. This means the hurricane no longer has a warm core that defines a hurricane, but it’s still a very strong wind storm.
This recently happened with Hurricane Ophelia, which hit Ireland and the United Kingdom. Ophelia was a Category 3 hurricane, so it was a major hurricane with winds over 100 miles per hour. It underwent a sort of transition and then still hit Ireland with winds at about 80 miles per hour.
So effects of hurricanes can be felt farther north from where they form.