I love going to the beach. My family used to go when I was young, and I got the bug. This year we planned a beach vacation in Florida, near Sarasota. So of course as we head down that way there is a hurricane getting more powerful every day in the Gulf of Mexico.
I decided to take this as a sign, and to find out a little more about these huge storms. It turns out that the name “hurricane” comes from “Hurakan,” the name of a Mayan god who used his breath to create storms and floods. When the Spanish arrived they heard about Hurakan and began to use the name to refer to these great storms.
Hurricanes start with warm water, which evaporates into the air. As warm air rises, the air pressure near the surface of the ocean decreases, which draws in more air, which gets heated and rises. As water vapor rises, it cools and releases heat and forms clouds. Then there is a factor called the Coriolis effect, in which the movement of the earth’s rotation curves moving air. As air moves toward the low pressure center of a storm, the Coriolis effect bends the air, making it swirl counterclockwise if north of the equator and clockwise if south. At the equator, there is no Coriolis effect, so hurricanes can’t form there.
Stronger winds develop as there is a larger pressure difference between the surrounding air and the center of the storm. This creates stronger thunderstorms near the center, causing greater warming and lower central pressure, which creates even stronger winds. The cycle is self-reinforcing as long as the path continues over warm water.
A storm goes through several stages before it is labeled a hurricane. It begins as a tropical cyclone, which is just a low-pressure system with thunderstorm activity and winds moving in a circular pattern. If the winds are moving at less than 39 mph, it is called a tropical depression. Over 39 mph it becomes a tropical storm. With winds of over 74 mph it is called a hurricane. Interestingly, if such a storm forms in the northern West Pacific Ocean, it is called a typhoon, not a hurricane.
The terrific winds of a hurricane are frightening, but the most damage is usually caused by storm surge — ocean water that the storm pushes ashore. These surges can reach 20 feet high. During Hurricane Katrina in 2005, one-third of the 1200 deaths that it caused were by drowning. Katrina caused damage estimated to be worth $125 billion.
It looks like the hurricane we are currently monitoring, Hurricane Isaias, is heading for the Gulf coast near Destin, Florida. Let’s hope the damage it causes is minimal.
