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a loud crash of thunder. Sometimes, a severe

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thunderstorm causes tornadoes . They start when
a sudden drop in air pressure creates a vortex.

Tornadoes can form whenever a warm front meets

a cold front. But so many tornadoes touch down

in the Midwest which is called Tornado Alley.

Hurricanes are the strongest and most

dangerous storms. They are caused by a warm

low pressure system that evaporates water from

oceans. In the United States, hurricanes are given

8
names, and they vary in strength from category
one to five. The strongest hurricane on record in

the United States was Camile. She was a category

5 storm that blew winds over 300 km/h and

destroyed entire cities along the Gulf of Mexico.

5 swirl : to move in circles
6 electricity : energy made available by the flow of an electric charge
7 tornado : destructive storm in the shape of a funnel cloud
8 strength : physical energy or intensity 13