Weather and Severe Storms

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Weather and Severe Storms
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The Sun provides the energy that drives Earths
weather by unevenly heating the land and water,
and by heating the equator and poles by different
amounts.
http//www.youtube.com/watch?v6hD52H7rQak The
Sun as the driving force behind for wind and
water currents and earths temperatures
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Air masses, of different temperature and
humidity, move from areas of high pressure to
areas of low pressure, creating wind.
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Why would the area indicated in the map below be
considered unseasonably warm?

• Look at the jet stream.
• Since the jet steam is so far north, the warm
  tropical air from the South would come further
  north

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Climate is the long term pattern of temperature
and precipitation in an area
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Weather is the short term variations in
temperature, humidity, air pressure, and wind.
http//www.climatecentral.org/videos/web_features/
climate_vs_weather
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Weather happens every day, but only some days
have storms
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Storms vary depending on their temperature, if
they are coming off the ocean or continent, and
the season.
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The severity of the storm depends on whether or
not they strike a populated area.
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Examples of severe storms

• Thunder and lightning storms
• Tornadoes
• Hurricanes
• Blizzards
• For the test you need to be able to
• distinguish one storm from another
• and
• identify why they only form in certain areas of
  world during certain times of the year

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Thunderstorms

• What is it?
• A storm with thunder and lightning and
  typically also heavy rain or hail.

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• What causes a thunderstorm?
• Moisture, unstable air, and lift.
• You need moisture to form clouds and rain. You
  need unstable air that is relatively warm and can
  rise rapidly. Finally, you need lift. This can
  form from fronts, sea breezes or mountains.

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• When are thunderstorms most likely to
  occur?Thunderstorms can occur year-round and at
  all hours. But they are most likely to happen in
  the spring and summer months and during the
  afternoon and evening hours. Why?

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• Warm, moist air rises, forming cumulus, then
  cumulonimbus clouds.
• The water vapor condenses, it collects together
  and forms rain drops or hail.
• As rain or hail falls, a downdraft is created,
  which cuts off rising warm air and stops the
  storm.

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Thunderstorm Formation
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Lightning

• Uneven electrical charges occur in a cloud as
  rain drops and hail move in a convection current
  in the cloud.
• The lightning occurs in an attempt to equalize
  the uneven charges.

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Tornadoes
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Tornadoes

• What is a tornado?A tornado is a violent
  rotating column of air extending from a
  thunderstorm to the ground.

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Other Names for Tornadoes

• Tornado comes from the Spanish word, tronada,
  which means thunderstorm. Other names for
  tornadoes are twisters, dust devils, whirlwinds,
  waterspouts, and cyclones.

R- Dust Devil, Center- Water Spouts, L- Fire Devil
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• In severe thunderstorms, winds are moving in
  different directions and at different speeds at
  different heights.
• This difference in wind direction and wind speed
  is called wind shear.

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Wave Clouds (or Tsunami Clouds, or
Kelvin-Helmholtz Clouds) seen in Van Goghs
Starry Night painting
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• A strong updraft tilts the wind shear and
  produces rotation inside the tornado. A funnel
  cloud appears.

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Tornado Alley

• Tornadoes in the U.S. are most likely to occur in
  a region known as Tornado Alley.

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• Did Dorothy from the Wizard of Oz live in
  Tornado Alley?

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Any place thunderstorms occur, a tornado can
happen. In the United Kingdom, Polar continental
air mixes with Tropical Maritime air producing
tornadoes
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Tornado Categories

• The Fujita-Pearson Tornado Intensity Scale or
  F-scale ranks tornadoes by their wind speed.
• F0- winds 40-72 mph
• F1- winds 73-112 mph
• F2- winds 113-157 mph
• F3 winds 158-206 mph
• F4 winds 207-260 mph
• F5 winds gt 261 mph

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Tornado Precautions

• Go to a basement, if you have one.
• Get in the innermost room of your house. Avoid
  rooms with windows. Bathrooms are good.
• Crouch with arms above your head.
• If outside, lie in a ditch or get under a bridge.
• If you live in an area with a frequency of
  tornadoes, listen to forecasts.

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Hurricanes
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Hurricanes

• What is a hurricane?Hurricanes are a system of
  strong winds spiraling inward and upward at
  speeds of 75 to 200 mph counterclockwise around a
  low pressure center
• Swirling air rises and cools, forming clouds and
  precipitation
• Hurricanes form over warm (82 degree ) water and
  have winds 74 mph

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Formation of a Hurricane

• Hurricanes are storms that form over tropical
  waters. The hurricanes that affect the eastern
  coast of the United States form off the western
  coast of Africa where the water is warm, the air
  is humid, and the winds converge.

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Tropical Disturbance

• Hurricanes start out as a group of storms that
  begin to rotate when they meet converging winds.
  These storms create violent seas that send more
  moisture into the air. The water vapor rises and
  helps the wind increase in speed. If the storm
  holds itself together for 24 hours, we call it a
  tropical disturbance.

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Tropical Depression

• Tropical cyclones are areas of low pressure that
  develop over tropical waters. We call them
  tropical depressions if their wind speeds are
  more than 25 mph and less than 38 mph.
• A tropical disturbance becomes a tropical
  depression if it lasts more than 24 hours.

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Tropical Storm

• A tropical depression becomes a tropical storm
  when its winds rise above 38mph.
• It is called a tropical storm if the winds are
  between 39 and 73 mph.

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Hurricanes

• A tropical storm becomes a hurricane when its
  winds exceed 73 mph.

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Hurricane Categories

• Category 1 Winds between 74- 95 mph
• Category 2 Winds between 96- 110 mph
• Category 3 Winds between 111-130 mph
• Category 4 Winds between 131-155 mph
• Category 5 Winds above 156 mph

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Hurricane Facts

• Hurricanes can be very big, even as big as the
  state of Ohio! They can be seen from outer
  space.
• The entire formation and life of a hurricane
  takes days or weeks.
• Because hurricanes seldom travel in straight
  paths, meteorologists predict several paths.
• Hurricanes usually lose power as they travel over
  land.
• Hurricanes destroy beaches, buildings, and
  vegetation.
• Hurricanes bring strong winds, heavy rain, storm
  surges, flooding, and tornadoes.

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Hurricane Protection

• Watch weather forecasts.
• Board up all windows and doors
• Have bottled water, food, batteries, medicine,
  and important documents
• Call someone and let them know where you are
• Photograph valuables for insurance
• Take care of your pets

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Hurricane Isabel
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Hurricane Andrew

• The path of Hurricane Andrew over three
  consecutive days can be seen below.

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Super Storm Sandy
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Blizzards

• A blizzard is a long-lasting snowstorm with very
  strong winds (35 mph) and intense snowfall.

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When and where do blizzards occur?

• They are common in winter when the jet stream
  travels south and a cold northern air mass comes
  in contact with a warmer, semi-tropical air mass.

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• When the cold, continental polar air mass travels
  over a lake, it can pick up more moisture and
  produce Lake Effect snow blizzards

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Lake Effect Snow
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Blizzards Ice Storms
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Review

1. Which is larger, a hurricane or a tornado?
2. Which moves faster, a hurricane or a tornado?
3. Which lasts longer?
4. Where do hurricanes form?
5. Where do tornadoes form?
6. What do we call the area of the US that has a
   high occurrence of tornadoes?
7. How long do tornadoes last?
8. How long do hurricanes last?
9. Name two precautions in the event of a tornado.
10. Name two precautions in the event of a hurricane.

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Severe Weather

Typical Time of Year
Type of Storm
Where Forms
Safety Rules
Within large cumulonimbus clouds
Seek shelter, avoid trees and water.
Spring or Summer
Thunderstorms
Move to a storm shelter or basement if possible
stay away from windows and doors.
Cumulonimbus cloud
Spring, early summer
Tornado
Evacuate or move inside a well-built building.
Late summer and into autumn
Over warm ocean water
Hurricane
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WEATHER SERVICE MAPS

• ISOTHERMS are lines joining places on the map
  that have the same TEMPERATURE
• Do you see the connection between isotherm and
  thermometer

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WEATHER SERVICE MAPS

• ISOBARS are lines joining places on the map that
  have the same AIR PRESSURE
• Iso means equal
• Bar means pressure
• Why doyou think its called a barometer?