Transcript:

Heres a program from our archives.Tornados and Airplanesambience: Airplane takeoff - JFKThere's a lot that we don't know about tornados, and the challenge is how to get near enough to investigate them without endangering lives and equipment. One solution is to look at other places where tornado-like formations, or vortices, appear. I'm Jim Metzner, and this is the Pulse of the Planet.Bedard: If anybody's ever been in an aircraft on a very humid day and you're landing in an airport, you'll actually be able to see the vortices around the wings of the aircraft. You should look for that, if you haven't seen that."Alfred Bedard is a supervisory physicist with the National Oceanic and Atmospheric Administration.Bedard: The heavier the aircraft, the more circulation there is around the wing and the more strength is given to the wakes behind the aircraft which appear as two counter-rotating vortices, right off of the tips of each of the wings and those are of the strength of tornadoes; they're just smaller. And that's why when you follow a very heavy aircraft, like a 747, in a light aircraft, you'll end up having to space yourself fairly far behind it, so that you don't get into that trailing wake. It's so strong that it could actually upset a following aircraft. So controllers are very careful to space aircraft so you don't get a heavy aircraft right in front of a very light aircraft.Scientists are particularly interested in the sounds produced by the vortices behind an aircraft. Understanding the nature of these sounds may one day help us to better detect tornadoes.Pulse of the Planet is presented by the National Science Foundation.