This has been a terrible year for tornadoes, with April 2011 setting the U.S. record for the most tornadoes in any month.
There can be little or no warning. One minute it’s just raining or hailing, and the next minute the roof or even the whole house is gone. If you were lucky, your family had a few seconds to dive into your basement — if you have one — and was not seriously injured.
With most weather events, you do have a few days or hours of warning. This early warning is thanks partly to hardworking satellites that keep a constant eye on Earth’s weather from space.
Precisely predicting tornadoes is a different story. Where do these violent storms come from? Why do they destroy some buildings, but not others nearby? And why can’t weather forecasters warn people of their exact path so they can get out of the way?
Certain conditions do make tornadoes more likely. But no one ever knows when, where, how intense, and how many tornadoes a thunderstorm will create.
Tornadoes start in thunderstorms. Inside a huge thundercloud, warm and humid air is rising, while cool air is falling along with rain or hail. This situation creates a spinning air current inside the cloud. One end of this spinning column of air can drop down out of the cloud like a finger reaching toward the ground. If it touches, it becomes a tornado.
The winds inside some tornadoes are the fastest on Earth. They can reach more than 300 mph. As the wind column spins, it also moves along the ground, leaving piles of splinters where once stood perfectly good buildings and trees.
Although current weather satellites can identify storms likely to produce tornadoes, a new kind of weather satellite, the GOES-R, will do a much better job. It will give weather forecasters more time to identify the storms that might produce tornadoes, and it will be much better at predicting their severity. In turn, this will help to give people more time to get out of a tornado’s way.
See what a developing storm looks like from space in several videos on the SciJinks weather website for kids at http://scijinks.gov. Play cool weather games while you’re there.
This article was written by Diane K. Fisher and provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.