Download Storms

Storms
Storms
• A storm is a violent disturbance in the
atmosphere
• 4 major types of storms:
– Thunderstorms
– Tornadoes
– Hurricanes
– Snowstorms
• A meteorologist is a scientist who studies
weather and tries to predict it
Thunderstorms
• A thunderstorm is a small storm often
accompanied by heavy precipitation and
frequent thunder and lightning.
• Form in large cumulonimbus clouds (also
called thunderheads) on hot, humid
afternoons
Thunderstorms
• Warm, humid air rises
rapidly and the air
cools, forming dense
thunderhead clouds
• Heavy rain falls,
sometimes along with
hail
• Within the
thunderhead cloud
there are strong
updrafts and
downdrafts
Lightning
• Lightning is a sudden spark, or electrical
discharge
• Positive and negative charges jump
between parts of a cloud, or between
nearby clouds, or between a cloud and the
ground
Thunderstorms
• Lightning heats the air to 30,000oC
• Thunder is the sound of the rapidly heated air
expanding suddenly and explosively
• Since light travels faster than sound we see
lightning before we hear thunder
Calculating Lightning Distances
1. Watch the sky for a flash of lightning.
2. Count the number of seconds until you hear
thunder.
3. Divide the number of seconds by 5 to calculate
the distance the storm is away from your location
in miles (or divide by 3 for kilometers).
• Practice: If you counted 20 seconds from when you
saw the lightning until you heard thunder, how far away
was the lightning strike?
4 miles
Divide Number of Seconds
by 3 for Distance in Km
or 5 for Distance in Miles.
Lightning Strikes in the U.S.
• This map shows how often lightning strikes different
parts of the lower 48 states. Central Florida has the most
intense concentration of cloud-to-ground lightning
because it has a lot of warm, humid air. The Pacific
Northwest has almost no lightning.
Thunderstorm Safety
• Go INSIDE!
• Do NOT touch
anything that can
conduct electricityespecially metal
objects and bodies of
water
• Crouch down in a low
area. Avoid trees!
Tornadoes
• A tornado is a rapidly whirling, funnelshaped cloud that reaches down from a
storm cloud to touch Earth’s surface
Tornado Formation
• Warm, moist air flows in at the bottom of
a cumulonimbus cloud and moves
upward
• A low pressure area forms inside the
cloud
• Warm air rotates as it meets winds
blowing in different directions at
different altitudes
• Part of the cloud descends to
the earth in a funnel
• Tornado Alley is an area of the United States
that has a high frequency of tornadoes because
cold, dry air moves south from Canada to meet
warm, humid air from the Gulf of Mexico
• 5 states that cross Tornado Alley are:
–
–
–
–
–
Texas
Oklahoma
Kansas
Nebraska
Iowa
The Fujita Tornado Damage Scale
• Tornadoes are ranked on the Fujita scale
by the amount of damage they cause.
Tornado Safety
• A tornado watch is an announcement that
tornadoes are possible in your area. Stay
tuned to the radio or television news.
• A tornado warning is an announcement
that a tornado has been sighted. Take
shelter immediately!
• The safest place to be during a tornado is
in a storm shelter or the basement of a
well-built building.
Hurricanes
• A hurricane is a tropical cyclone that has winds of 119 km/h or
higher
• Hurricanes form in the Atlantic, Pacific, and Indian Oceans
• In the western Pacific Ocean, hurricanes are called typhoons
• A hurricane begins over warm ocean water as a low-pressure
area, or tropical disturbance.
• A hurricane draws its energy from the warm, humid air at the
ocean’s surface
• As the air rises and forms clouds, more air is drawn into the
system
• Inside the storm are bands of very high winds and heavy rains
• Winds spiral inward toward the area of lowest pressure at the
center
Hurricane Names
• Hurricanes are given names to help us identify
them and track them as they move across the
ocean
• Men and women's names are used
• One name for each letter of the alphabet except
Q, U, and Z
• World Meteorological Organization uses six
lists in rotation
• The only time a new name is added is if a
hurricane is very deadly or costly
• If that happens then the name is retired
and a new name is chosen.
2008
2009
2010
2011
2012
2013
Arthur
Bertha
Cristobal
Dolly
Edouard
Fay
Gustav
Hanna
Ike
Josephine
Kyle
Laura
Marco
Nana
Omar
Paloma
Rene
Sally
Teddy
Vicky
Wilfred
Ana
Bill
Claudette
Danny
Erika
Fred
Grace
Henri
Ida
Joaquin
Kate
Larry
Mindy
Nicholas
Odette
Peter
Rose
Sam
Teresa
Victor
Wanda
Alex
Bonnie
Colin
Danielle
Earl
Fiona
Gaston
Hermine
Igor
Julia
Karl
Lisa
Matthew
Nicole
Otto
Paula
Richard
Shary
Tomas
Virginie
Walter
Arlene
Bret
Cindy
Don
Emily
Franklin
Gert
Harvey
Irene
Jose
Katia
Lee
Maria
Nate
Ophelia
Philippe
Rina
Sean
Tammy
Vince
Whitney
Alberto
Beryl
Chris
Debby
Ernesto
Florence
Gordon
Helene
Isaac
Joyce
Kirk
Leslie
Michael
Nadine
Oscar
Patty
Rafael
Sandy
Tony
Valerie
William
Andrea
Barry
Chantal
Dorian
Erin
Fernand
Gabrielle
Humberto
Ingrid
Jerry
Karen
Lorenzo
Melissa
Nestor
Olga
Pablo
Rebekah
Sebastien
Tanya
Van
Wendy
Hurricane Formation
Hurricanes
• Hurricanes last longer than other storms, usually a week
or more
• After a hurricane passes over land, it no longer has
warm, moist air to draw energy from so it loses strength
• A storm surge is a “dome” of water that sweeps across
the coast where a hurricane lands
• For safety during a hurricane, people are told to
evacuate
• Evacuate means to leave the area immediately
Snowstorms
• All year round, most precipitation begins in
clouds as snow
• In California, snowstorms generally occur
only at high elevations (i.e. Mt. Shasta or
Sierra Nevada)
The Danger of Snowstorms
• High winds during a snow storm can
reduce visibility
• Strong winds can also cool a person’s
body very rapidly
• Roads & doorways
can be blocked
Quick Review
1. Name the 4 main types of storms.
thunderstorms, tornadoes, hurricanes, & snowstorms
2. How do you calculate lightning distance?
Divide the number of seconds between lightning & thunder arrival by 5 to
calculate the distance away in miles (or divide by 3 for kilometers).
3. Name 2 ways to be safe during a thunderstorm.
Go inside, do not touch anything that can conduct electricity, crouch
down in a low area, avoid trees.
4. What speed does a tropical storm need to reach to
be considered a hurricane?
119 km/hr (73 miles/hour)