You need to take cover if you ever see a dark cloud that is shaped like a funnel and pointed toward the ground. Warn people that you have seen a tornado nearby. Tornadoes are powerful, swirling winds. Tornadoes can tear roofs off of houses. They can smash brick buildings. Tornadoes can pick up cars and trucks. People can be badly hurt or killed by flying wood, glass, and other things blowing around in a tornado.
WHERE DO TORNADOES COME FROM?
Tornadoes come from big thunderstorms. Tornadoes drop down from the bottoms of storm clouds. Tornado winds blow in a circle. You can’t normally see wind, but you can often see a tornado because its strong winds pick up dust and dirt. A tornado looks like a big, dark funnel coming from the bottom of a storm cloud. Some tornadoes look like a swinging elephant’s trunk. They sound like a freight train going by. Tornadoes cause damage when the bottom of the funnel touches the ground.
HOW LARGE AND FAST ARE TORNADOES?
Tornadoes can be huge. The biggest tornadoes are almost 1 mile (almost 2 kilometers) across. The average tornado is about 160 feet (about 50 meters) across. Tornado winds whirl very fast. They whip around at speeds from 75 miles per hour (120 kilometers per hour) to almost 300 miles per hour (500 kilometers per hour). Sometimes a tornado almost stands still in one place, but tornadoes usually move. They can move forward at speeds up to 70 miles per hour (110 kilometers per hour).
HOW POWERFUL ARE TORNADOES?
It is hard to study tornadoes. Scientists never know quite when or where they will appear, and they move fast. In 1971, a scientist named Theodore Fujita made up a scale to tell how powerful a tornado is. His Fujita scale ranks tornadoes by how much damage they do. The scale goes from F0 to F5. Weak tornadoes are F0 and F1. Weak tornadoes may damage chimneys and break tree branches. Powerful F5 tornadoes can pick up houses off the ground and strip the bark off of trees.
ARE THERE TORNADOES ALL OVER THE WORLD?
Tornadoes can form anywhere, but they are more common in some places than in others. The United States gets the most tornadoes. Australia also gets many tornadoes. There are more tornadoes in spring than in any other season. Tornado Alley is a place in the Midwestern United States where many tornadoes form. Tornado Alley goes from parts of Texas northward through parts of South Dakota . Another place that gets many tornadoes is Dixie Alley. It goes from southern Texas to Florida .
WHAT SHOULD YOU DO IF A TORNADO COMES?
The National Weather Service sends out tornado watches and warnings on radio and television. A tornado watch means that tornadoes might form in the next few hours. A tornado warning means that a tornado has touched down, or that someone has seen a funnel cloud. It can also mean that scientists have seen a tornado on a radar screen. You should find shelter right away if you hear a tornado warning. Go to a basement if you can. If you can’t get to a basement, get into a closet, an inside hallway, or a bathroom in the middle of the house. Stay away from windows. Get out of mobile homes and cars. Tornadoes can blow them away. Get out of auditoriums, gymnasiums, supermarkets, and other buildings with big roofs. The roofs could fall down in a tornado. If you are outside, lie flat in a ditch and cover your head to protect it from wood, glass, and other things flying around in the air. Scientists are trying to learn more about tornadoes. They want to get better at predicting tornadoes. Better predictions would warn people early. Early warnings about tornadoes could save many lives.
Hurricane
A hurricane is coming! Boards are nailed over big store windows. Families pack their cars and leave town. A hurricane is a powerful storm with pouring rains and strong winds. Hurricanes can do a lot of damage. They cause floods. They blow down trees. Windows break and roofs fly off of houses.
WHERE DO HURRICANES COME FROM?
Hurricanes start over the ocean. They form over warm water near the equator. The equator is an imaginary line that goes around the middle of the planet. Some hurricanes start in the North Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico . These hurricanes can strike the East Coast or Gulf Coast of the United States . Hurricanes generally do not hit the West Coast, and rarely make it as far north as Canada . In the western Pacific Ocean , hurricanes are called typhoons. Hurricanes near Australia and India are called tropical cyclones.
The winds of a hurricane blow in a huge circle. There is a calm place called the eye in the center of the circle. All around the eye are thick, tall clouds. Heavy rain pours down from these clouds. Hurricanes move across the water. They grow stronger if they stay over warm water. Some hurricanes head for land. Hurricanes can do a lot of damage if they come up on land. But hurricanes grow weaker the farther inland they go. They also grow weaker over cold water.
HOW STRONG ARE HURRICANES?
Weather scientists called meteorologists study hurricanes. They rank hurricanes in categories from 1 to 5. The weakest hurricane is a Category 1. It has winds that blow at least 74 miles per hour (120 kilometers per hour). The strongest hurricane is a Category 5. It has winds that blow at more than 155 miles per hour (250 kilometers per hour). The strongest hurricane of the 20th century was Hurricane Gilbert. It hit the island of Jamaica and parts of Mexico in 1988. Gilbert had winds that gusted up to 218 miles per hour (350 kilometers per hour). One of the most destructive hurricanes in recent history was Mitch, which killed about 18,000 people in Central America in 1998. Another destructive hurricane, Andrew, happened in 1992. Andrew killed more than 50 people. It destroyed thousands of homes.
CAN HURRICANES BE PREDICTED?
Meteorologists watch for hurricanes at sea during summer and autumn. When a hurricane forms out in the ocean they watch it very carefully. They use radar, weather satellites, and instruments in the sea. They try to figure out which way the hurricane is traveling. Sometimes special airplanes fly into the hurricane to make measurements. Meteorologists warn people when a hurricane is headed their way. They tell people to board up their windows. They tell people to leave the area. Predicting hurricanes can save many lives.
