Transcript Tornado - Moore Middle School

These are the major types of severe weather that
we will learn about today
•Thunderstorms
•Tornadoes
•Hurricanes
A storm is a violent disturbance in the atmosphere.
They involve sudden changes in air pressure, which
cause rapid air movements
Thunderstorms are heavy rain
storms accompanied by thunder
and lightning.
Thunderstorms form within large cumulonimbus
clouds, or thunderheads
Watches- when conditions
are favorable to produce a
thunderstorm
Warnings- Issued when a
thunderstorm has already
formed and is happening
Cold Front
Most form when warm air is forced upward at a cold front.
They can also form on hot, humid afternoons in the spring and summer.
In both cases, this is when warm, humid air rises rapidly.
Areas of positive and negative electrical charges
build up in the storm clouds during
thunderstorms
Lightning is a sudden spark, or energy discharge,
as these charges jump between the parts of a
cloud, between nearby clouds, or between the
cloud and ground
What causes thunder??
Lightning can heat the air around it as high as
30,000C which is hotter than the surface of the
Sun!!
This heated air expands rapidly, suddenly, and
explosively.
Thunder is the sound of that explosion.
Why do I see lightning before I hear it?
Because light travels faster than sound, you will
see lightning first! Think about a baseball
game, you see the player hit the ball before you
hear the crack of the bat.
Thunderstorm Safety Tips
•Avoid metal objects
•Stay out of water
•Avoid electrical appliances,
bathtubs or showers, and
landlines, which can all
conduct electricity
A tornado is a rapidly whirling, funnel-shaped cloud
that reaches down from a storm and touches
Earth’s surface
Tornadoes develop in low, heavy cumulonimbus
clouds
Tornadoes occur more often in the United States
than any other country.
About 800 tornadoes occur in the US every year
The Great Plains often have the type of weather patterns
necessary for tornadoes
Cold, dry air mass moves south from Canada and meets warn,
humid air from the Gulf of Mexico
A squall line of thunderstorms can develop and can produce
ten tornadoes or more
Tornado Alley includes north-central Texas, central Oklahoma,
Kansas, and Nebraska, but any state could have a tornado
Tornado watch means that conditions exist that
could produce a tornado
This means that you should pay attention to weather
reports in case the weather should worsen or
produce an actual tornado
Tornado Warning means that a tornado has been
spotted on radar on in person, and you should take
cover in a safe place
During a tornado, a “safe place” would be the most
interior room in a house on the lowest level, away
from windows and doors.
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Tornadoes are measured based on their wind
speed/damage.
The Fujita scale is used to measure the intensity
of a tornado by examining the damage caused
by a tornado after it as passed over an area
Hurricanes begin as a low pressure area, or tropical
disturbance , over warm water
Hurricanes get their energy from the warm, humid air at the
ocean’s surface.
This air rises and forms clouds, drawing more air into the
system
Winds spiral inward toward the low pressure inside
Inside the storm are bands of high winds and heavy rains
The lowest pressure and warmest air is at the center of the
hurricane in the eye
The “Eye” of the hurricane is the center, “quiet” area. If you were
to be in the path of this hurricane, you would notice that the
winds get stronger and rain heavier as the eye approaches.
In the eye, there would be calm winds and maybe even a clear
sky.
Then the eye would pass and the storm would resume, with the
wind blowing in the opposite direction
One of the most dangerous features of a hurricane is the storm
surge.
Low pressure and high winds of a hurricane can raise the water up
as much as 6 meters above normal sea level
The result is a storm surge, or dome of water that sweeps on shore
How bad is bad?
Hurricanes are measured based
on the strength of their winds
They start as tropical
depressions,
then advance to tropical storms,
then advance to hurricanes
Once winds are at least 74 mph,
they are a Category 1 hurricane
Strongest hurricanes in US history
Name of Hurricane
Category
Florida Keys (1935)
5
Hurricane Camille (1969)
5
Hurricane Andrew (1992)
5
Name of Hurricane
Amount of Damage ($)
Katrina
81 billion
Andrew
26.5 billion
Wilma
20.6 billion