Meteorology

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Meteorology

• 12.1 The Causes of Weather

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Weather

• Meteorology is the study of atmospheric phenomena
• Weather is the current state of the atmosphere.
• This is usually measured in minutes, days and
  weeks

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Climate

• Climate is the weather for a long period of time
  for a given location.
• Usually averaged over 30 or more years.
• Ex. The climate is hot and humid in Miami, but it
  is snowing there today.

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Air Masses

• An air mass is a large body of air that takes on
  the characteristics of the area over which it
  forms.

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Types of Air Masses

• Moisture
• Maritime vs. Continental
• Maritime air masses form over water- have more
  moisture
• Continental air masses form over land- they are
  drier

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Types of Air Masses

• Temperature
• Tropical vs. Polar
• Tropical air masses form closer to the equator-
  warm
• Polar air masses form closer to the poles- cold
• Arctic air masses are extremely cold

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Source Regions

• Combine Moisture and Temperature titles to name
  air masses.
• Name them after the regions where they form.
• Continental Tropical(cT) will form over land near
  the equator. Ex. Brazil, Mexico
• Maritime Tropical(cM) will form over water near
  the equator. Ex. Gulf of Mexico

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Examples

• Continental Polar(cP)
• Continental Tropical(cT)
• Maritime Polar(mP)
• Maritime Tropical(mT)
• Arctic(A)

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Coriolis Effect

• The Earth spins on its axis. This causes air
  particles to deflect to the left in the N.
  Hemisphere to the right in the S. Hemisphere

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R
L
L
R
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Wind Systems

• Three wind zones in each Hemisphere
• Trade Winds
• Prevailing Westerlies
• Polar Easterlies

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• Wind Zones
• The trade winds occur from the equator to 30ºN
  and 30ºS. The winds at the equator are called the
  doldrums and the ones at the 30º mark are called
  the horse latitudes.
• The prevailing westerlies are between 30ºN and S
  up to 60ºN and S in a pattern opposite of the
  trade winds. They are responsible for moving most
  weather across the US and Canada.

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• The polar easterlies are between 60ºN and S and
  the poles. (90ºN and S)

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Jet Stream

• A stream of air that circulates the globe. Caused
  by differences in pressure between the wind
  systems.
• Trade and Westerlies
• Westerlies and Easterlies

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Fronts

• A front is the narrow region separating two air
  masses of different densities. These differences
  are due to differences in temperature, humidity,
  and pressure.
• Cold
• Warm
• Stationary
• Occluded

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Page 308- 309 in RED BOOK!
Cold Front Cold dense air displaces warm air
and forces the warm air up along a steep
front -Thunderstorms often occur along the front
On a weather map solid blue line with blue
triangles that point in direction of the fronts
motion
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Cold Fronts

• Cold Fronts occur when a cold air mass runs into
  a warm air mass, forcing the warm mass to
  rise.(notice cloud types!)

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Warm Front Advancing warm air displaces cold
air - Extensive cloudiness and precipitation
On a map solid red line with regularly spaced,
solid red semicircles pointing in the direction
of the front's motion.
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Warm Fronts

• When warm masses run into cold masses and slowly
  displaces it. (notice clouds!)

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Stationary Front Two air masses meet and
neither advances air masses stall - Light wind
and precipitation
On a map combination of short segments of cold
and warm front symbols
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Stationary Fronts

• Stationary Fronts occur when front run in
  parallel opposite directions

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Occluded Front Cold air mass moves so rapidly
that it overtakes a warm front - Strong winds,
heavy precipitation
On a map alternating purple triangles and
semicircles that point toward the direction of
motion.
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Occluded

• Occluded Fronts occur when two cold fronts
  pinch a warm front up.

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Front Video
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High Pressure Systems

• High Pressure Systems- Air sinks, then hits the
  Earths surface and spreads out.
• Wind blows away from high pressure.
• Clockwise in N. Hemisphere
• Associated with fair weather

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Low Pressure System

• Low Pressure System- Air rises, must be replaced.
• Wind blows toward center of low pressure
• Counter-Clockwise in N. Hemisphere
• Associated with clouds and precipitation

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