Journal W-5
There are two types of pressure systems
that are related to weather. Name them
and the type of weather associated with
each.
There are basically 5 types of severe weather
that form from low pressure systems that
affect the United States
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–
–
–
–
Thunderstorms
Tornados
Tropical storms
Hurricanes
Winter Storms
A. Thunderstorms
1. Found near cold fronts as cold air pushes
warm moist air rapidly into the atmosphere.
2. Lifecycle (about 1 hour)
a. Cumulus-15 minutes of strong winds
moving up (updraft)
b. Mature-30 minutes of heavy rain, strong
wind, lightning, maybe hail
c. Dissipating-15 minutes of downdrafts
overtake updrafts and the storm loses
energy
http://www.wiley.co
m/college/strahler/04
http://www.youtube.com/watch?v=_c
71480533/animation
l0aw87LqA&feature=player_detailpa
s/ch06_animations/in
ge
dex.html
3. Thunder and Lightning
a. lightning is caused by the attraction of
opposite charges inside a cloud or between
the cloud and the ground.
1.
2.
3.
4.
5.
6.
Kills over ____ people per year
Hotter than the ________
__________million strikes in US per year
______people struck in a year only ____survive
_______occurring at any given moment on Earth
Ice particles build up. Large particles have a ____ charge
and small particles have _____ charge. When they collide,
lightning is formed
http://www.youtube.co
7. The result is a bolt of ______ amps
m/watch?v=p-5Qra8. Travels 200 000 feet per second
Ms64&feature=player_
detailpage
b. Thunder is caused by the rapid heating (up to 30000
0C) of air around lightning-like a shock wave
4. Supercell thunderstorms are much larger,
more powerful, and last for several hours.
Supercells may lead to the formation of
tornadoes.
http://www.youtube.com/wat
ch?v=36vGiE5JQzs&feature
=player_detailpage
http://www.youtube.com/watch?v=
Teis2gCCLw&feature=player_detailpage
http://www.youtube.co
m/watch?v=HaGdxy5er
I0&feature=player_deta
ilpage
Orange-gust front
Red-Storm Front
Yellow-Advance Storm Pics
• http://www.youtube.co
m/watch?v=khLcpi2H http://www.youtube.com/watch?v=
ptM&feature=player_ 37nsUIIMkeE&feature=player_det
ailpage
detailpage
http://www.youtube.com/watch?v=
RqqCESrorc&feature=player_detailpage
Very cool stuff. BUT…. If the hair on
your arm stands up GET LOW AND
RUN!
B. Tornadoes-a violently rotating
column of air
1. Arise from differences in air pressure called wind
shear
2. Can only be seen because of the debris it picks up
3. Tornadoes are 400-500 feet wide. *
4. Tornadoes have winds around 100 miles per hour.*
5. Tornadoes last only a few minutes.*
6. Very destructive
7. Tornadoes occur most often in the spring (AprilJune)
*Some are bigger and last longer-this is average
8. About 1200
occur globally
each year. 75%
of all tornadoes
occur in the
United States
along “Tornado
Alley,” an area
that runs from
Texas to Illinois.
http://dsc.discovery.com/videos/won
ders-of-weather-extremeweather.html
http://www.youtube.com/watch?v=cvOut9VUqKY&feature=
player_detailpage
9. Tornado are categorized using the Fujita Scale or F-scale. It
ranks tornadoes by their wind speed. Range is F0-F5. 85%
are F0-F1
•
•
•
•
•
•
F0 (Gale)
F1 (Weak)
F2 (Strong)
F3 (Severe)
F4 (Devastating)
F5 (Incredible)
http://esminfo.prenhall.com/science
/geoanimations/animations/Tornado
es.html
http://www.youtube.com/wat
ch?v=jLrcXFoPbHI&feature
=player_detailpage
C. Tropical Storm-a storm that
forms from a low-pressure
system(sometimes called tropical
disturbances or depressions) with
winds of 40-73 mph
D. Hurricanes-A tropical storm
becomes a hurricane when its winds
exceed 73 mph. They form over the
Atlantic ocean
1. Other names
a. Indian Ocean-called a
typhoon
b. Pacific Ocean-called a
cyclone
• http://www.youtube.com/watch?v=HJydFJ
ORWf4&feature=player_detailpage
2. Hurricane Facts
a. They can be 600 miles across.
b. Hurricanes move very slowly and last for days
c. Hurricanes have a spiral shape, like a
pinwheel. The main body is called the eye wall
with winds moving counter-clockwise.
d. At the center of a hurricane is a calm area 20
to 30 miles wide called the eye.
e. Hurricanes cause damage through: high winds,
heavy rain, storm surge, and flooding.
f. Hurricane season runs from June through
November.
g. They can be seen from space
http://www.youtube.com/watch?feature=player_detailpage&v=eT5K6FR_eVs
Picture from the International
Space Station
h. Because hurricanes seldom travel in
straight paths, meteorologists predict
several paths.
i. Hurricanes usually lose power as they travel
over land or cold water.
j. Hurricanes destroy beaches, buildings, and
vegetation.
k. Hurricanes bring strong winds, heavy rain,
storm surges, flooding, and tornadoes.
**A storm surge is a large mass of ocean
water that mounds up in the middle of
the hurricane and then crashes inland
causing flooding
http://www.youtube.com/watch?v=mJbfGUylkR0&feature=
player_detailpage
l. Hurricane Categories: The Saffir-Simpson
Scale
•
•
•
•
•
Category 1 -- Winds 74-95 mph
Category 2 -- Winds 96-110 mph
Category 3 -- Winds 111-130 mph
Category 4 -- Winds 131-155 mph
Category 5 -- Winds over 155 mph (these are
VERY rare)
M. They start as low pressure systems over warm
water. This is where their energy comes from.
http://www.youtube.com/watch?v=gVkMwo26smk&feature=player_detailpage
http://www.youtube.com/watch?feature=player_detailpage&v=gd8WiiXNxho
Hurricane Isabel
http://www.youtube.com/watch?v=uLJS0
KccI8U&feature=player_detailpage
E. Winter Storms
a. Blizzard-A snow storm with wind gusts of
35 mph or more
b. Lake Effect Storms-heavy snowfall near
Great Lakes
c. Ice Storms-rain falls onto already cold or
freezing ground
http://www.youtube.com/watch?fea
ture=player_detailpage&v=5v2Lm
DUzscM
Review
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
Which is larger, a hurricane or a tornado?
Which moves faster, a hurricane or a tornado?
Which lasts longer?
Where do hurricanes form?
Where do tornadoes form?
What do we call the area of the US that has a high
occurrence of tornadoes?
How long do tornadoes last?
How long do hurricanes last?
Describe three common winter storms.
Explain the lifecycle of a thunderstorm.
What causes lightning and thunder?
What is a supercell?
How is a hurricane different from a tropical storm?
Name the scales used to classify a tornado and a
hurricane.