Hurricanes,Typhoons, and Cyclones, Oh my: The Basics on Tropical Storms

By Lauren Matthews

Fig. 1:  Hurricane Fran of the coast of Florida, as seen from space

http://rsd.gsfc.nasa.gov/rsd/images/Fran19960904color3a_lg.gif

Even if you don’t live near the East coast you still know when hurricane season is. This is because of the wide spread news of hurricanes throughout the US. Hurricanes, also known as tropical storms, are large storms formed over the ocean in low pressure areas. Due to now being hurricane season you may have heard of a lot of hurricanes, such as Hurricane Hermine and, most recently, Hurricane Matthew. With hurricane season in full swing it is good to know the basics on hurricanes and tropical storms, even if you aren't preparing for one.

What’s the difference between Hurricanes, Typhoons, and Cyclones?

There is no difference between these tropical storms except the location they formed in. Hurricanes are tropical storms that formed in the Western Hemisphere, north of the equator. Typhoons are tropical storm that formed in the Eastern Hemisphere, north of the equator. All storms that formed in the Southern Hemisphere are cyclones.

Fig 2: A map of how tropical storms are named

http://spaceplace.nasa.gov/hurricanes/en/

Interestingly a hurricane or typhoon cannot become a cyclone because of the earth’s rotation. This is known as the Coriolis Effect. The Coriolis Effect is what causes hurricanes and typhoons to turn counterclockwise, thus pulling them away from the equator. Cyclones turn clockwise due to the Coriolis Effect, also pulling away the storm from the equator.  

Hurricane Categories

You have probably heard of a hurricane category before but do you know what it means? Hurricanes are classified into groups based on wind speed. This is used to calculate how dangerous the hurricane will be if and when it achieves landfall. Even though all hurricanes are dangerous, a category one hurricane will be less dangerous and destructive than a category five hurricane.

The scale used to measure hurricane categories is called the Saffir-Simpson Hurricane scale. The wind speed mentioned in the chart is the sustained wind speed and is measured in the eye of the storm. The storm surge is the change of water level due to pressure changes and storm winds.

Although the scale gives levels of damage for each category, it is not always accurate. It mostly depends on where the hurricane has landfall. A category three storm in a highly populated area could do as much damage as category five storm in a less populated area. Damage is more about location of landfall than wind speed to some extent.

Importance of Hurricane Knowledge