"The largest, most sophisticated tornado chase ever assembled has been roaming the Great Plains for the past five weeks looking to crack some of the basic mysteries about the wildest storms on Earth.
Known as Vortex 2, the experiment winds down Saturday. The original Vortex in the mid-1990s inspired the movie Twister, in which scientists pursued tornadoes past flying tractors and right through an intact, rolling farmhouse.
The actual roving experiment hasn't been quite that kind of a white-knuckle ride, but it's a lot more important because understanding tornadoes will save lives. Even the answer to a seemingly simple question such as 'how do tornadoes start?' isn't yet known. So the federal government is spending $12 million to try to find out."