Transcript Storms 1 ppt. – Doug

2. What conditions are needed
for a hurricane to form?
a. Warm ocean water (above 800F)
b. Low air pressure
c. High humidity (very moist air)
d. Coriolis effect
If any of these are missing, a hurricane cannot form!
3. Hurricanes usually begin their development
over ocean water west of Africa.
the warm waters west of Africa.
Hurricane Classifications
Category 1: Minimal (wind speeds from 74 – 95 mph)
Category 2: Moderate (wind speeds from 96 – 110 mph)
Category 3: Extensive (wind speeds from 111 – 130 mph)
Category 4: Extreme (wind speeds 131 – 155 mph)
Category 5: Catastrophic (wind speeds faster that 155 mph)
A hurricane is like a spinning merry-go-round. When
you're on the edge of a merry-go-round you're moving
really fast. The closer you move to the center, the easier it
is to stand up--this is the "eye" of the merry-go-round!
Wind can't get into the eye of a hurricane because of the
same forces that made it hard for you to get to the center
of the merry-go-round.
Eye
http://www.windows.ucar.edu
A storm surge is
1. caused by strong winds pushing water up
onto shore higher than normal;
2. the MOST damaging part of a hurricane.
LIGHTNING and THUNDER!
1. During a thunderstorm, areas of positive (+)
and negative (-) electrical charges build up in
the storm clouds.
2. Lightning is a sudden spark of energy that can
a. travel within a single cloud (most common)
b. travel from cloud to ground
c. travel from cloud to cloud (least common)
1. A lightning bolt heats the air near it,
and the heated air expands suddenly
and explosively. Thunder is the sound
of the explosion.
NOTE: Since light travels faster than
sound, you see lightning before
you hear thunder.
Lightning injures and kills more
people per year than hurricanes or
tornadoes; between 75 to 100 people.
Double Strike!!
F-Scale
Wind Speed
F-0
F-1
F-2
F-3
F-4
F-5
40-73
73-112
113-157
158-206
207-260
261-318
F-O
F-5
WEAKEST
STRONGEST
Be sure you know the difference
between a tornado watch and a
tornado warning!
Watch – Conditions are favorable
for a tornado to occur in your area.
Warning– A tornado has
touched down in your area!
Name several safe places where you could go
during a tornado warning?
1. is a heavy snowstorm with
very cold temperatures;
2. has sustained winds of at
least 35mph;
3. will have a visibility of less
than ¼ of a mile.
A rapidly intensifying low pressure center
stalled off the southern New England coast
for more than 24 hours. Blizzard conditions
and coastal flooding were the big stories in
this storm, as hurricane force winds drove
an angry sea onshore, causing great damage
to coastal property. Snowfall amounts on the
order of 30 to 38 inches fell in and around
the Boston metropolitan area. The storm
paralyzed New England for a week.
 The Great Blizzard of '49 was the worst blizzard the
U.S. has ever known. This famous blizzard also known
as the "Great White Death" was actually a series of
blizzards that lasted for seven weeks. They began in
Wyoming and Colorado, then spread over most of the
West. To save cattle and sheep, the U.S. Air Force
dropped 1,500 tons of hay. More than 100 people and 1
million heads of livestock were killed in this deadly
blizzard.
1.
2.
A flash flood is the fastestmoving type of flood. It happens
when heavy rain collects in a
stream or gully, turning the
normally calm area into an
instant rushing current.
MOST flash floods are caused by
spring rains and melting snow.
Flash flood - Cincinnati 1997