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COPYRIGHT 2006 Science Weekly, Inc.
Hurricanes!! (Hur-ri-canes!!)
If you stood right in the center of a hurricane, the air would be still and calm. If you looked up, you might see the sun shining and a few clouds floating by. This is called the eye of the hurricane.
But, walk 25 km in any direction and you will be entering the eyewall (eye-wall) of the hurricane. There, the winds blow as fast as a speeding car and can go higher than 300 km per hour. That's a strong enough wind to blow down buildings and large trees. How Do Hurricanes Start?
Hurricanes begin as storms over the ocean. They need warm air, so they always start in tropical (trop-i-cal) regions. Water from the ocean evaporates (e-vap-o-rates) into the warm air and is carried upward. When this water vapor rises high enough to bump into colder temperatures, it condenses (con-denses) into clouds. These clouds can reach 18 km into the sky.
How do these clouds turn into the terrible winds of a hurricane? Since the earth is rotating, the rising air molecules twist into a counterclockwise spiral (spi-ral) in the northern hemisphere and into a clockwise spiral in the southern hemisphere. As the water vapor condenses, it releases energy, causes the wind to move faster and faster, and creates a hurricane. In the Path of a Hurricane
Hurricanes may begin at sea, but they don't stay there. They are blown by the normal flow of wind from east to west. The spiraling motion of the hurricane adds to this movement making it difficult to predict when and where the storm will find land.
Not all the damage from a hurricane is caused by the wind. Since these storms begin over the ocean, they push along a wall of water as they move. This is called the storm surge. The storm surge can be high enough to wash away everything in its path. What can be done about Hurricanes?
In the 1940s and 1950s, scientists tried to seed storms. Extremely cold dry ice was dropped into the clouds of a hurricane. Scientists hoped that the water in the clouds would then turn to ice crystals and fall as snow or rain. These attempts ended in the 1970s.
The focus now is on predicting the paths of hurricanes so that people can move safely out of the way.
DID YOU KNOW??
Most hurricanes occur between June 1 and November 30
Hurricanes are helpful by moving warm air to colder regions.
How A Hurricane Forms
1. Warm tropical ocean waters evaporate and spiral upwards.
2. Colder air rushes down, creating spiraling winds.
3. Clouds form above, swirling in a counterclockwise direction.
Weekly Lab
Many of the tools that scientists use to study the weather may look complicated, but they are based on very simple ideas. A barometer (ba-rom-e-ter) measures air pressure. Low pressure is needed for a hurricane to begin Make your own barometer!
You need: a clean, empty coffee can, plastic wrap, a rubber band, a drinking straw, glue, a ruler, paper and pencil
Step 1: Wrap the plastic wrap over the opening of the coffee can.
Step 2: Wrap a rubber band around plastic wrap so it will be air tight.
Step 3: Glue the straw to the top of the can with about two-thirds of the straw on the plastic...
Read the full article for free courtesy of your local library.
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