Weather and Climate

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Weather and Climate
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What is weather?

• The interactions of the air pressure,wind,
  temperature and moisture in the atmosphere.

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Humidity

• Moisture in the atmosphere. The moisture is
  held between gases in the atmosphere.

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Humidity

• Warm air gas molecules spread out far, so there
  is more space for water vapor.

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Humidity

• Cold air gas molecules move closer together, so
  there is less space for water vapor and the extra
  vapor is squeezed out.

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Humidity

• How does temperature affect humidity?

the warmer, the more humid.
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Changes in Weather
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Air Masses

• A body of air that has the same properties as
  the area which is has developed.

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Examples

• 1. Formed over oceans - moist
• 2. high latitudes - cool
• 3. low latitudes - warm

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Fronts

• When two air masses meet they tend not to mix
  The area that separates the two is called a front.

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Fronts

• 1. Warm Front develops when a warm air mass
  meets a cold air mass. The warm air, because it
  is less dense, slides up over the cold air.

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Fronts

• 2. Cold Front forms when a cold air mass
  invades a warm air mass. The cold forces the
  warm air to rise rapidly. Cooler temperatures
  follow the passage of a cold front.

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Fronts

• Stationary Front forms when either a warm front
  or cold front stops moving forward. This type of
  front may remain in the same place for several
  days.

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Fronts

• Occluded Front- results when two cool air masses
  merge, forcing the warmer air between them to
  rise. High winds and heavy precipitation are
  associated with this front.

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Clouds

• Clouds form when water vapor condenses. Fog and
  mist are just low clouds.

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Types of Clouds

• Cumuluscauliflower shaped with flat bases. Can
  extend high in the sky. Associated with fair
  weather.

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Types of Clouds

• Cirrusthin, white , feathery cloudsForm high in
  the sky contain ice crystals because they are so
  high in the skyassociated with fair weather but
  may indicated approaching storms.

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Types of Clouds

• Nimbusrain-bearing clouds of all types they are
  usually dark and thick with ragged edges.
  Example Cumulonimbusrain-bearing clouds
  associated with thunderstorms, rainfall, and hail.

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Types of Clouds

• Stratusform relatively near the earths surface
  in flat layers associated with light drizzle.

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How Precipitation is formed

• Rainwhen the water droplets collide to form
  larger water droplets they fall to the surface as
  liquid precipitation.

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How Precipitation is formed

• Sleetwhen raindrops pass through air that has a
  temperature below freezing, the rain drops
  freeze.

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How Precipitation is formed

• Hailwhen wind tossed the freezing drops
  repeatedly through warm and cold layers of air,
  many layers of ice build up.

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How Precipitation is formed

• Snowflakeswhen the water vapor condenses into
  tiny ice crystals instead of water drops.