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How Strong Is That Hurricane?
The wind blows. The rain comes down. Hurricanes are powerful. They can rip a house apart. They can wipe out cities. But how do they start? And how do you know how big it will be? How can you tell how strong it is?

A world map with purple continents and orange places in the blue waters near the equator
Image above: Hurricanes form in water. The orange parts show where they form. Credit: NASA

Let's figure it out.

Hurricanes start over the ocean. They need three things:

  1. Warm water
  2. Damp air
  3. Winds that meet
When the wind blows at least 74 miles an hour, it is called a hurricane. That is very fast! It is faster than a car drives on a highway. Sometimes the winds blow faster than that.

Parts of a Hurricane

There are three main parts of a hurricane:
  1. Eye -- This is the center. It is the calm part of the storm.
  2. Eye Wall -- This part is around the eye. This part has the strongest winds and rains. The winds may blow 200 miles per hour.
  3. Rain Bands -- These are the clouds that spin out and make the storm bigger.
Drawing of a hurricane that has been cut to see the inside. Inside is the eye which is a hole down the middle from top to bottom; the eye wall is around the eye; the rest are the rain bands.
Image above: There are three main parts of a hurricane.
Credit: NASA
How Strong Is It?

Hurricanes can destroy what they hit. The winds can blow things down. The water can cover homes. The rains can cause floods. We can know how strong a hurricane is. There is a scale that is used to measure them. It is called the Saffir-Simpson Hurricane Scale. A hurricane can be on a scale of one to five. A level one does not destroy as much as a level five does.

Click on each picture
to see the movies.
One: There is not much damage. Picture of low water going towards a house and small pieces of the roof blowing off
Two: The winds blow at about 100 mph; it may break windows and destroy trees. Higher water going towards a house and bigger pieces of roof blowing off
Three: It breaks windows and doors. Water almost as high as the top of the door going towards a house and windows and roof breaking
Four: There is much damage. Very high water going towards a house and big pieces of roof breaking leaving big holes and part of the house has moved
Five: This is the worst; winds blow at least 155 mph. It destroys buildings. Water as high as the top of the door going towards a house and the house is beginning to fall from the strong winds

Adapted from Fierce Force of Nature: Hurricanes
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