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Josh Wurman's heart raced as he sped through town. Behind him, a monster tornado roared. If it caught him, it could toss his truck like a toy.

Normally, Wurman does the chasing. He is a meteorologist. He studies storms. A tornado is one of the most dangerous kinds of storms.

A tornado's winds can spin up to 483 kilometers (300 miles) per hour. They can be deadly. Power lines break. Roofs fly off buildings. Tornadoes can rip up everything in their path.

Wurman was lucky. He got away. He wasn't near the tornado for a thrill. He wanted to learn about it.

Scientists like Wurman already know a lot about tornadoes. Yet they don't know exactly how these storms form. That information is important.

It could help them predict when tornadoes will strike. Then they could do a better job warning people that a tornado is coming. They could save lives. That's why Wurman wants to solve tornado mysteries.

Tornadoes are hard to study. Getting close to one can be deadly. It's hard to find them, too. They don't last long. They can happen all over the world. They can happen during the day or at night, and any time of year.

There are some tornado hot spots, though. One is called "Tornado Alley." It's in the United States. The wind patterns there cause big thunderstorms called supercells.

Wurman knows about Tornado Alley. That's why he went there to hunt tornadoes in the spring of 2009. He joined a team of weather scientists. It was the biggest tornado study ever.

First, the scientists had to find tornadoes. Each day, they checked weather reports. They looked for supercells. When they spotted one, they raced to reach it. Often, they got to it too late. Sometimes, a twister never formed. Week after week, they failed to find a twister. They didn't give up, though.

Finally, the team got lucky. A big storm formed in Wyoming. The sky turned black. Winds whipped. This time, the team got there in time.

Inside his truck, Wurman watched his radar screens. He saw lots of colors. He "read" the colors. They showed him where rain fell and winds spun. They made a map of the storm.

First, warm, moist air rushed up into the the cloud. That rising air is called an updraft. At the same time, a cooler downdraft pushed rain and hail to the ground.

Up in the cloud, the rising and falling winds began to spin faster and faster. They made a funnel. It touched the ground. It was a tornado!

The tornado looked like an elephant's trunk. Its tip wiggled across the ground. Wurman's team dropped weather tools in its path. The tools measured the tornado's wind speed and direction. They also measured air temperature. They even measured the size of raindrops and hail.

After 30 minutes, the funnel started to wobble. Then it was gone.

That tornado gave Wurman and his team lots of data. It told them more about tornados than ever before. Of course, there is still a lot to learn.

They have to figure out what it all means. For example, why do some supercells spin out tornadoes and others don't? It's like putting a puzzle together. This puzzle could take 10 years to solve.

The answers could lead to better tornado forecasts. People would have more time to scramble to safety when a tornado is coming. For Wurman, that would be an even bigger thrill than seeing another tornado up close.

Article by Diane Wedner. Top-of-page image by Priit J. Vesilind/National Geographic Stock. "Twister" appears in the April 2011 issue.