"The trick is being in the right place at the right time before the storm develops," Samaras says. "That's what everybody struggles with." So far this year he has clocked about 20,000 miles (32,000 kilometers) on his vanstorm chasing is mostly, after all, chasing.
Once Samaras has found his developing storm, he relies less on technology and more on his senses, as surface observations become key.
He pulls over to study the shape and movement of a mass of clouds, looking for clues that the storm might spawn a tornado. As the storm catches up with him, he jumps back in the van and races ahead again, hoping he'll find himself at the right coordinates if a tornado develops.
Samaras gets it right about two out of every seven outings. And a few times he's been right in its path.
"It takes me about 10 seconds to deploy the probe," Samaras says. A videotape shows him racing from the van, dropping the probe on the ground and speeding away as two-and-a-half-inch hail falls around him and the tornado approaches.
In a dispatch sent on Monday, Samaras wrote of the previous night's adventures just west of York, Nebraska. "It was simply amazing! This storm dropped four-and-a-half-inch hail. We watched a beautiful cone funnel drop halfway to the ground last night, got into position just a quarter of a mile away, only to watch the funnel dissipate! I guess that's part of the game."
Predicting Tornado Strength
"Tim's work is essential for the next VORTEX experiment," says Rasmussen. In 1994-1995 Rasmussen led the Verification of the Origin of Rotation in Tornadoes Experimentor VORTEXwhich was a scientific tour de force featuring cars, portable radar devices, planes, balloons and "turtles," with a mission to understand tornado formation.
"There have been successful attempts to measure pressure inside a tornado," Rasmussen says, "but Tim is the first to measure the temperature, humidity, and wind speed and direction."
What practical applications will emerge from these measurements are still unclear. "It is still a bit of a fishing expedition," Rasmussen adds. With more data from a range of tornadoes, he speculates, the measurements may prove useful for predicting the intensity and duration of future tornadoes.
"We currently have about an 80 percent false alarm rate when it comes to predicting which storms will spawn tornadoes," says Penn State's Markowski. "All research we do is directed at reducing that rate, and Tim's work is a step in that direction."
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