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Storm Formation
Chapter 7
Lesson 2 (part 2)
- Storms
Thunderstorm Formation
•A thunderstorm forms when warm, humid air
rises rapidly within a cumulonimbus cloud.
What is a thunderstorm?
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Warm air rises.
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Charges build
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Cool air sinks.
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Positive electric charge
Negative electric charge
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- Storms
Tornado Formation
•Tornadoes can form when warm, humid air
rises rapidly in thick cumulonimbus clouds—the
same type of clouds that bring thunderstorms.
- Storms
Tornado Alley
•Tornadoes in the U.S. are most likely to occur in
a region known as Tornado Alley.
- Storms
Structure of a Hurricane
•In a hurricane, air moves rapidly around a lowpressure area called the eye.
What are hurricanes?
dry air
sinking
upper-level winds
eye
direction of rotation
low-level winds
flowing toward center
- Storms
Hurricane Andrew
•The path of Hurricane Andrew over three
consecutive days can be seen below.
- Storms
Lake-Effect Snow
•As cold dry air moves across the warmer water,
it becomes more humid as water vapor
evaporates from the lake surface. When the air
reaches land and cools, snow falls.