AMES, Iowa -- Their job is to take measurements of a tornado's rear flank downdraft.
And yes, said several Iowa State University students who have joined Tim Samaras, a Colorado-based researcher who was named a National Geographic Society "Emerging Explorer" in 2005 and is a principal engineer for Applied Research Associates Inc., some adrenaline is involved. But that's not why they're driving instrument-carrying cars a mile or so to the south or east of the storms that have regularly blown across tornado alley this spring and summer.
They're driving into rain, wind, lightning and hail to chase data: temperature, dew point, barometric pressure, wind speed, wind direction and exact location. The students' measurements will be analyzed by scientists trying to understand more about how tornadoes are formed.
"We're measuring air circulation near the tornado," said Chris Karstens, an Iowa State graduate student in meteorology from Atlantic. "There are questions about that air's role in forming tornadoes and in tornado longevity. We think it has a central role in tornadoes."
Karstens, who spent five days on the road with Samaras' crew last month, said he saw and chased about 12 tornadoes. Most were weak storms. But he saw a few that were a mile wide or bigger.
Bill Gallus, an Iowa State professor of geological and atmospheric sciences, said this is the third year Iowa State students have done field research with Samaras. They're generally on the road throughout May and June. Students volunteer to be part of Samaras' "TWISTEX" (Tactical Weather Instrumented Sampling in/near Tornadoes/Thunderstorms EXperiment). Those selected are usually experienced storm chasers and have done well in forecasting courses. The students are not paid, but their field expenses are covered. The students' research is part of an Iowa State project supported by the National Oceanic and Atmospheric Administration and led by Partha Sarkar, an Iowa State professor of aerospace engineering and director of the Wind Simulation and Testing Laboratory.
The idea is to send students out to the field to learn more about how storms develop and evolve, Gallus said. They also learn about working with mobile instruments and taking measurements.
"They come back and they're so excited about the data they can analyze," Gallus said.
They're also excited about the stories they can tell.
Brandon Fisel, a graduate student in meteorology from Hebron, Ind., remembers May 29 near Osborne, Kan. That's when Samaras dropped three probes containing cameras and instruments in the path of an oncoming tornado. The probes took a direct hit and could yield the first measurements of wind speed at the bottom of a tornado.
W Scott Lincoln, a graduate student in environmental science from Alleman, likes to talk about the day he drove through a tornado that was just beginning to form. He didn't know what was happening at the time, but the car's weather instruments later confirmed the storm had begun to circulate over his head.
Jayson Prentice, a senior meteorology student from Terril, says his time with Samaras' experiment can help him build his research resume for graduate school.
And what about the chase? Does it get scary when the storms kick up, as they have all too often this tornado season?
Well, said Karstens, most of the experiment "is just like you're on a very long road trip" because the researchers drive hundreds of miles from storm system to storm system.
Prentice remembers the intensity of "a few moments when we were taking near-tornado windfall readings within a mile or a couple of miles of tornadoes. One tornado was over a mile wide."
But, said Fisel, "the adrenaline is kind of going and you don't feel scared at all."
Besides, said Lincoln, the researchers aren't "yahoo chasers going out for thrills." They're calling in reports to the National Weather Service. They're recording as much data as they can. And they're working to help scientists develop a better understanding of the deadly and destructive storms.