Meteorology

Severe Storms

What are thunderstorms?

Very common storms that cause electric sparks called lightening that heat the air and cause the noise called thunder.

They usually have heavy rains and strong winds and sometimes hail.

They often happen when the weather is hot and a cold front is approaching.

They are formed in 3 stages…

Stage 1

Intense heating causes air to rise quickly and form a cloud. More and more moist air is carried up and the cloud grows larger. When the clouds can’t support the moisture anymore it falls as heavy rain or hail.

Stage 2

Once the rain falls the air in the cloud moves downward. When the air going up rubs the air going down it causes static electricity. When enough of this builds up there is lightening.

Lightening slams into the air around it with such force that it makes thunder.

Stage 3

A thunderstorm ends when the air moving down becomes stronger than the air moving up.

Heavy rain lightens and stops.

Where do thunderstorms usually form?

In the warm air just ahead of a cold front.

How and where do tornadoes happen?

The most violent thunderstorms can turn into tornadoes.

They form where dry, cold air masses mix with warm, moist air masses. In the U.S. this is most likely to happen in the Great Plains region and the Mississippi Valley and also in Florida.

They happen most often in early spring and summer.

BRAIN POP VIDEO

Hurricanes

7. Hurricanes are very large, swirling storms with very low pressure at their center. They form over tropical oceans near the equator. See p. D70-D71.

Hurricane Ivan

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