Linda F. Malanson
(figure available in print form)
Hurricanes are the biggest and most powerful of all storms. They are circular and vary in size many of them are roughly 650 km (400 miles) in diameter, and wind speeds can reach 200 km/h (125 mph) or more.
Hurricanes form over warm, tropical seas when the water temperature is above 80 degrees Fahrenheit. They do not form on the equator or beneath jet streams.
Once formed, they follow a path away from the equator, usually growing in intensity while they remain over warm water. They dissipate over cool water or over land. Such storms are called hurricanes if they form in the Atlantic, cyclones around India and Australia and typhoons in the western Pacific.
EXPERIMENT: MODEL HURRICANE
(figure available in print form)
The clouds around a hurricane form spiral bands. In them water vapor condenses in the warm, rising air. This releases latent heat, helping the air to continue rising.
At high altitude the air enters the region of high pressure, adding to the pressure difference between the top and the bottom of the storm.
Some of the energy in the cloud is then transferred to the clear air next to each spiral band and increases the wind speed. You can make a ”hurricane” vortex in water showing that spiraling water also forms bands.
MATERIALS NEEDED:
1. eye dropper
2. food coloring
3. plastic hand mixer
4. bowl—preferably a clear plastic one
5. water
DIRECTIONS:
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1. Fill the bowl with lukewarm water. The bigger the bowl, the better. Stir the water gently until it is all moving slowly in a circle around the bowl.
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2. Release a few drops of food coloring into the center of the bowl. Watch the color move out and form bands—just as clouds in a hurricane do.
(figure available in print form)
EXPERIMENT: STORM SURGE
(figure available in print form)
A hurricane is seen in clouds and winds. Its winds affect the ocean surface. Much of the damage caused by a hurricane is due to the oceans lapping on the shore with great intensity.
Rainfall is heavy and winds produce waves up to 15 m (50 ft.) high. This effect is widespread and waves are often much larger than normal as much as 1,500 km (900 miles) from the eye of the storm. Fiercely pounding waves ahead of the storm can be 3 m (10 ft.) high.
When the hurricane approaches a coastline, strong onshore winds cause water to pile up in a “storm surge”. If the surge coincides with a high tide, sea water may sweep inland. This experiment shows you how to make a storm surge at home. ADULT SUPERVISION IS REQUIRED FOR THIS EXPERIMENT.
MATERIALS NEEDED:
1. electric fan
2. paper
3. grease pencil
4. scissors
5. tape
6. water
7. dishpan
DIRECTIONS:
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1. Make a funnel out of paper and tape its wide end to fit over the fan. This will concentrate the wind.
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2. Fill the dishpan with water to within about 5 c (2 in.) of the brim. Mark the water level at one end of the pan with the grease pencil. Position the fan so that it will blow towards the mark.
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3. Have an adult switch on the fan so that the wind blows across the surface of the water. How much does the water rise above the mark at the far end? (This is a “storm surge”.)
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4. Now repeat step 3, but tilt the dishpan a little to raise the water level near the mark, creating a high tide. See how much difference the tide make to the “storm surge”.