| Tornadoes are
rated by wind speed The
Enhanced Fujita Scale:
EF-0
65-85
mph; Light damage
EF-1.
86-110; moderate damage
EF-2.
111-135 mph; Considerable damage
EF-3.
136-165; severe damage
EF-4.
186-200 mph; devastating damage
EF-5.
Above 200 mph; incredible damage
Tornado Safety
Weather Dude Fun Fact: The biggest hailstone ever measured was 7 inches in diameter and
18.75 inches in circumference. It fell in a storm at Aurora, Nebraska, on June 22,
2003.
The previous record-holder as the largest hailstone
had a diameter of 5.7 inches and a circumference of 17.5 inches, and was found in
Coffeyville, Kansas, on September 3, 1970.
It still holds the record for the heaviest hailstone, weighing more than 1 1/2 pounds!
Lightning Countdown
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Terrifying Twisters
Some severe thunderstorms may produce
tornadoes. These are violently rotating
columns of air in contact with the Earth’s surface. The United States has more
tornadoes than anywhere else on earth, with about one thousand occurring every year. The wind inside a tornado can reach speeds of more
than 200 mph. Government meteorologists may issue a
tornado watch if they think
thunderstorms could be severe enough to produce tornadoes. If someone reports a tornado, or if weather radar indicates a thunderstorm
is strong enough to produce a tornado, local National Weather Service meteorologists issue
a tornado warning. If you hear a tornado
warning, act quickly and get to a closet or hallway on the lowest floor of your home, away
from outside walls and windows until the danger passes. It is best for your family
to have an emergency plan before storms hit.
Go here for some ideas. Ice from the Sky
Hail forms in strong
thunderstorms. These storms contain very strong updrafts, which are winds blowing up
through the thunderstorms clouds. They can be as strong as one hundred miles per
hour. Those strong updrafts suspend rain in mid-air with temperatures around the
raindrop of below 32 degrees. Those cold temperatures allow the rain to freeze into
small hailstones. As more freezing raindrops get caught in the updraft, they collide
with the hailstones, adding layer after layer of ice. When hail becomes too heavy for
the updrafts to keep it aloft, it falls to the ground. In strong updrafts, the hail
has time to collect lots of ice, so the hail is bigger. In weak updrafts, the hail
doesn't have to get as big before it is able to fall to the ground. Sometimes the
updrafts can be so strong that the hailstones can grow larger than softballs!
Rain So Heavy
Rainfall in a thunderstorm can be very heavy. Cumulonimbus clouds contain huge
amounts of moisture. Several inches of rain can fall in a short time. That's
why thunderstorms sometimes
result in flooding.
Experiments:
1. How Far Away?
The next time you see lightning, count
the seconds until you hear thunder. Since light travels faster than sound, the sound
of thunder takes longer to get to you; about five seconds to travel one mile. If you
count to five just before you hear the thunder, the lightning is about one mile
away. If it is very close, the thunder will sound like a loud crack. If the
lightning is far away, it will sound more like a low rumble. If the lightning is more than
fifteen miles away, you may not hear it at all.
2. Thunder Boomer
Blow up a small paper bag. Pop
it. What happened? You made the air inside expand quickly, the same way air
expands when heated by lightning. You made thunder!
For Further study and
activities:
What
causes thunderstorms
The Science
of Lightning
Center for
Learning Science Kits
Science Kits
Science Kit for
Student Use
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©Copyright 2012 Nick Walker/Small Gate Media
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