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SCIENCE NOTES - WEATHER
LESSON 8 (Chapter 11)
What are Thunderstorms?
- Thunderstorms are the most common severe storms. They usually
have lightning, heavy rain, and strong winds.
- Thunderstorms are created when intense heating causes air to rise
quickly.
- When it rains in the thunderstorm it creates a downdraft in the cloud.
When this rubs against the updraft, it causes friction, creating
lightning.
- The most violent thunderstorms often help create tornadoes. These
are caused by a strong updraft in a convection cell. As the air rushes
in, it curves into a spin.
- Most tornadoes occur in the Midwest and the South.
How Do Hurricanes Form?
- A hurricane is a very large, swirling storm with very low pressure.
- Strong heating and lots of evaporation over the ocean can cause a
large low pressure to form. This creates a ring of tall thunderstorms.
- The Coriolis Effect causes winds to spiral counterclockwise, pulling
clusters of thunderstorms in and making one big storm.
- The lower the air pressure, the faster the winds blow in the center of
the storm.
- When a hurricane is fully formed, there is an area of light winds and
clear skies in the center called the eye.
- The hurricanes storm surge usually causes the most damage. When
air pressure drops in a hurricane, the water rises. When the
hurricane moves over land, it can cause the water to rise several feet.
How Can Radar Track Storms?
- Radar works by sending out radio waves and recording their echo. A
change in the echo tells you something about where it reflected.
- Doppler radar can tell where precipitation is moving and can detect
spinning in the clouds.