Two Spinning Storms
1Hurricanes and tornadoes are two of the most powerful storms on Earth. Both are made of strong winds that spin around and around. Both can knock down trees and damage buildings, so people pay close attention when either storm is on the way. However, these two storms are different in many important ways.
2The two storms begin in different places. A hurricane forms over warm ocean water. The warm water heats the air above it and gives the storm its energy. A tornado, on the other hand, usually forms over land. It reaches down from a very strong thunderstorm.
3The storms are also very different in size. A hurricane is huge. It can be hundreds of miles wide, and it often lasts for several days. Unlike a hurricane, most tornadoes are less than a mile wide. Most of them last only a few minutes before they fade away.
4A tornado forms in steps. First, a strong thunderstorm builds up in the sky. Next, winds inside the storm begin to spin. Then a spinning funnel cloud may reach down from the bottom of the dark storm cloud. Finally, when the funnel touches the ground, it becomes a tornado.
5What happens when a hurricane moves over land? Over land, the storm can no longer get energy from warm ocean water. As a result, its winds slowly grow weaker. Even so, a weakening hurricane can bring heavy rain for days, which can cause floods.
6Because the storms are so different, the warnings for them are different too. Weather scientists can watch a hurricane on satellite pictures as it crosses the ocean, so people often know days ahead that it is coming. A tornado forms much more quickly. Tornado warnings may give people only a few minutes to get to a safe place, such as a basement or a small inside room with no windows.