Sample Unit - Texas ESL for Longman Cornerstone and Keystone

Up in the Clouds
The cold air makes the water vapor turn
back into water droplets or ice crystals.
That forms a cloud. Inside the cloud,
the droplets and crystals carry a tiny bit
of electricity. The electricity builds until
lightning suddenly forms.
Lightning can jump from one cloud
to another (see image 1). It can move
from a cloud to the ground (see image 2).
Sometimes lightning can even move from
the ground up to a cloud (see image 3).
Lightning is five times hotter than the
sun. Lightning heats the air around it so
quickly that the air explodes. Thunder is the
noise we hear when the air explodes.
Catch Me If You Can!
Light moves faster than sound. This
means we see the flash of lightning before
we hear the thunder. It takes five seconds
for the noise of the thunder to go one mile.
If you see lightning and then hear thunder
five seconds later, the storm is one mile
away. If thunder comes ten seconds after
lightning, the storm is two miles away.
droplets very small drops of liquid
crystals little pieces of ice
Before You
Go On
2
3
Why do we see lightning before we
hear the thunder?
Cloud-to-ground lightning
Ground-to-cloud lightning
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