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Period _______ Date _______________________
Thunderstorms
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Answer these Questions
What is a thunderstorm?
A thunderstorm is a storm with lightning and thunder. Its
produced by a cumulonimbus cloud, usually producing gusty
winds, heavy rain and sometimes hail.
What causes a thunderstorm?
The basic ingredients used to make a thunderstorm are
moisture, unstable air and lift. You need moisture to form
clouds and rain. You need unstable air that is relatively
warm and can rise rapidly. Finally, you need lift. This can
form from fronts, sea breezes or mountains.
1) Thunderstorms are
produced by
_____________________
clouds.
2) Thunderstorms need
_______ air to form clouds
and rain.
3) It also needs
________air that is warm
and can rise fast.
4) Finally, it also needs
_______, in the form of
_______ or sea ________.
5) In a thundercloud, bits
of ______ bump into each
other and these collisions
cause an
________________.
6) Positive charges or
_________ form at the
______ and negative
charges or _______ form
at the _______ of the
cloud.
What causes lightning? (Sky)
Lightning is an electric current. Within a thundercloud
way up in the sky, many small bits of ice (frozen
raindrops) bump into each other as they move around in
the air. All of those collisions create an electric charge.
After a while, the whole cloud fills up with electrical
charges. The positive charges or protons form at the top
of the cloud and the negative charges or electrons form
at the bottom of the cloud.
What causes lightning (Ground)
Since opposites attract, that causes a positive charge to
build up on the ground beneath the cloud. The grounds
electrical charge concentrates around anything that
sticks up, such as mountains, people, or single trees. The
charge coming up from these points eventually connects
with a charge reaching down from the clouds and - zap lightning strikes!
7)Opposites ________, so
positive charges build up on
the ________.
8) These charges collect
around anything that
___________.
9) These positive charges
on the ______connect with
the negative charges from
________, and zap!
So, What is thunder?
The sound of thunder is caused by lightening. The
lightening is so hot, that it heats the surrounding air
extremely fast. The air then expands because of the
heat. This expansion of air happens to so quickly that the
air actually breaks the sound barrier and that is the
thunder!
When are thunderstorms most likely to occur?
Thunderstorms can occur year-round and at all hours. But
they are most likely to happen in the spring and summer
months and during the afternoon and evening hours. It is
estimated that there are around 1,800 thunderstorms
that occur across our planet every day.
10) Thunder is the result of
super ________ air
expanding really
______________.
11) Most thunderstorms
occur in the __________
and ________ months in
the ___________ and
evening hours when the air
is
(think!)______________.
Thunder and Lightning Illustrations
1. On a hot, humid summer day, strong rising convection currents of warm air
grow into a cumulonimbus cloud.
2. Negative and positive charges are attracted to each other. As the charge
becomes stronger the attraction grows. To relieve itself it creates a giant spark,
lightning, that jumps the space separating the charges.
3. Thunder is the sound made when a lightning bolt heats the air and the air
expands quickly-the air explodes! Thunder and lightning happen at the same time.
You just see the lightning first because light travels faster than sound.
I counted 30 seconds
between the time I
saw lightning and
heard thunder! How
far away is it? _____
4. There are strong currents inside the cloud causing ice crystals within the cloud
to rise and fall. They become heavier and heavier until the air currents cannot
keep them up. They fall to the ground as ice and rain. This is the end of the
storm and the cloud will break up.
How does lightning strike high places?