The National Weather Service said there were ten reports of tornadoes across the central and southern Plains states last Thursday.

VOA: special.2011.04.19

Sunny, tornadoes, thunderstorms... very different.

晴天、龙卷风、暴风雨……各种各样。

来自田纳西 - SpeakingMax英语口语达人

The goal of the project is to examine in detail how tornadoes are formed and the kinds of damage they cause.

VOA: special.2010.05.11

They are hoping to surround tornadoes in the second and final year of an international project known as VORTEX2.

VOA: special.2010.05.11

Tornadoes form when winds blowing in different directions meet in the clouds and begin to turn in circles.

VOA: special.2010.05.11

It says tornadoes kill eighty people and injure one thousand five hundred others nationwide in an average year.

VOA: special.2010.05.11

Tornadoes form when winds blowing in different directions meet in the cloud and begin to turn in circles.

VOA: special.2009.06.09

The most severe tornadoes can reach wind speeds of three hundred twenty kilometers an hour or more.

VOA: special.2010.05.11

Last month, American scientists began work on a project aimed at improving the ability to predict tornadoes.

VOA: special.2009.06.09

The team is using forty cars and trucks to chase tornadoes, dropping measuring instruments in their paths.

VOA: special.2009.06.09

Tornadoes usually travel in a northeasterly direction with a speed of thirty-two to sixty-four kilometers an hour.

VOA: special.2010.05.11

They are using radars and other equipment to learn more about how, why and where tornadoes form.

VOA: special.2009.06.09

More than sixty tornadoes were reported in the country's southeast during the last weekend in April.

VOA: special.2010.05.11

At least twenty-nine people were killed in Tennessee, Mississippi and Kentucky, either by floodwaters or tornadoes.

VOA: special.2010.05.17

This area, from west Texas to southwest Minnesota, is where the most violent tornadoes usually happen.

VOA: special.2009.06.09

This time,scientists hope to learn more about the formation, wind speed and shape of tornadoes.

VOA: special.2009.06.09

To safely capture up-close film footage of tornadoes, some project participants traveled in a seven-ton, armored tornado intercept vehicle directly into tornadoes as they formed.

VOA: special.2011.04.19

But each year there are some surprises where tornadoes develop when they are least expected.

VOA: special.2010.05.11

The area where the most violent tornadoes usually happen is known as "Tornado Alley."

VOA: special.2010.05.11

Tornadoes have been known to carry homes,cars and trees from one place to another.

VOA: special.2010.05.11

Last year, tornadoes killed more than one hundred people in the United States.

VOA: special.2009.06.09

They are the severe thunderstorms that produce the most deadly and destructive tornadoes.

VOA: special.2009.06.09

But tornadoes cover a much smaller area than hurricanes, which form over oceans.

VOA: special.2011.04.19

It is called Verification of the Origins of Rotation in Tornadoes Experiment Two.

VOA: special.2009.06.09

They measure tornadoes on the Enhanced Fujita scale or the EF scale.

VOA: special.2011.04.19

Tornadoes can be measured using wind speed information from Doppler radar systems.

VOA: special.2010.05.11

And,when they observe them, they can advise people that tornadoes might develop.

VOA: special.2011.04.19

Researchers also observed several other powerful storms that were not tornadoes.

VOA: special.2010.05.11

Weather experts operate warning systems to tell people about possible tornadoes.

VOA: special.2009.06.09

Some night-time tornadoes have been observed because of lightning strikes nearby.

VOA: special.2011.04.19