Hurricane Exhaust

4:46 pm in Did You Know?, Tropics, Weather Education by Ted Keller

Air Flow in a Hurricane

As I recently informed my Introduction to Atmospheric Science students, well developed hurricanes have a feature you might not expect.

Everyone focuses (no pun intended) on the eye and eye wall and they should…it is awesome to watch and is the most powerful part of the storm.

Hurricanes spin cyclonically or counter-clockwise, a rotation initiated by the earth’s rotation. But if you look closely at the satellite loop of Danielle from Friday, the high, thin-looking clouds on the edges are actually arcing outward and have a slight anticyclonic or clockwise rotation, the opposite of what is happening below!

The reason for this behavior lies in the temperature profile of a developed hurricane. The massive amount of convection or thunderstorms in the center of these storms is releasing a tremendous amount of heat energy. This creates a warm bubble of air over the top and center of the storm. This in turn creates a relative area of high pressure which cause air to flow outward which is what is revealed in the cloud motion.  The whole system is what meteorologists call a warm core low.