Transcript Severe Weather Notes

Severe Weather
Notes and information
BIG IDEA
 The root of all weather is the Sun, which
heats the Earth. The heating is uneven,
because of night and day, because different
surfaces (such as rocks and trees) absorb
and reflect sunlight in different amounts, and
because sunlight hits the equator more
directly than the poles. Uneven heat creates
pressure differences, and wind flows
between areas of high and low pressure.
Thunderstorms
Thunderstorm is storm
with thunder, lightning,
heavy rains and strong
winds; form within large
cumulonimbus clouds;
usually form along a
cold front but can form
within an air mass.
Click on the links below:
Thunderstorm Formation Animation
Real Thunderstorm Animation
How they Form
• Form within large cumulonimbus clouds.
• Warm air is forced upward by a cold front.
• Warm air rises extremely quickly; cools and
condenses just as fast to form huge dense
clouds (anvil).
Characteristics: Lightning and Thunder
• Positive and negative
charges build up in
clouds.
• Lightning is a sudden
spark as charges
jump from one cloud
to another.
• Thunder is caused by
the rapid heating of
the air.
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Characteristics: When and Where?
• Most Likely to form
on hot humid days
• Spring and Summer
• Occur in areas
where cold fronts
are common
(just about anywhere)
**To be “severe” it must have ONE OR MORE of the following:
• Winds at least 57.5 mi/hr
• Hail ¾” or larger
• Tornado
Thunderstorm Safety
Avoid metal objects
Try not to be the tallest object in an
area
Find a low area away from trees, fences
and poles.
Make yourself as small as possible.
Stay out of the water
Avoid touching electrical appliances or
phones.
Interesting Facts
• You can calculate your
distance from a storm.
# of sec. / 3 s/km = distance(km)
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Lets Try…
At any given time there
are 1800 storms on
Earth.
80 die from lightning each
yr.
Winds can exceed 160
km/hr.
Causes hundreds of
millions of $$ in damage
each yr.
Tornadoes
•A tornado is a rapidly whirling,
funnel-shaped cloud that extends
down from a storm cloud; the very
low pressure and strong winds can
cause great damage to people and
property.
•Tornadoes are likely to form within
the frontal regions where strong
thunderstorms are also present.
•Click on the link below to do the
animation:
Tornado Wind Patterns Animation
How They Form
1) Develop in low heavy
cumulonimbus clouds.
2) Warm air rises so fast
that it creates an
updraft.
3) As it rises it begins to
rotate
4) At the same time, cold
air drops just as fast and
creates a downdraft
5) Updraft grows more
narrow, and spins faster.
Another
view
Play Animation
Where and When
(characteristics)
• Occur in Spring or
Summer
• Associated with
T-Storms
• Tornado Alley….
Tornado Alley
• The Great
Plains…
Why?..........
Warm, moist air
from the Gulf
rises and meets
with cold dry air
from Canada.
Interesting Facts:
• Wind speeds can
reach up to 480
km/hr.
• More common in
US than any other
country
• Biggest threat is
flying debris
Tornado Safety
Tornado watch = they are possible
Tornado Warning = one has been seen
Go to the basement of a well-built
building.
Stay away from windows and doors
Lie under a steady piece of furniture
Duck and cover
If outside: lie in a ditch
Now….Some cool pictures
Hurricanes
•A hurricane is a low pressure
tropical storm that forms over
warm ocean water; winds form a
spinning circular pattern around
the center, or eye, of the storm.
•The lower the air pressure at the
center, the faster the winds blow
toward the center of the storm.
•Click on the link to watch the
video:
Hurricanes 101 Video
How they form
• Begins over warm water in a low pressure area
• Warm humid air from ocean water rises to form
clouds
• Winds spiral inward toward low pressure.
When and Where: Characteristics
• Forms in the summer
and fall over the
oceans
• Winds can be as
strong as 320 km./hr.
• Last a week or more
• Loses strength after
reaching land.
• Play animation
Special Features: Characteristics
• The eye is the center
of the hurricane which
has very calm
weather.
• Storm Surge huge
rush of water that
arrives with
hurricanes.
Saffir-Simpson Scale
category 1: minimal (119-153 km/h)
category 2: moderate (154-177 km/h)
category 3: Extensive (178-209 km/h)
category 4: Extreme (210-250 km/h)
category 5: Catastrophic (over 250 km/h)
Hurricane Safety
Hurricane watch = conditions are
possible
Hurricane warning = conditions are
expected.
Evacuate the area
Move to the interior of a building away
from windows.
Stay well above sea level
Interesting Facts
• Typical hurricane is
600km. Across
(Andrew was only 60 km)
• Hurricane Andrew cost
over $25 bill.
• Andrew was only 1 of 3
that hit the US to be
classified as a category 5
hurricane
• In the Pacific it is called a
typhoon
The
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