Weather and the Water Cycle

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Weather and the Water Cycle

• Chapter 8

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The Atmosphere

• The blanket of air surrounding the Earth.
• Very thin and made up of several layers.
• Each layer has a different temperature.
• The closet layer to the Earth is the troposphere.
  
• Air pressure is the weight of the atmosphere
  pressing down on the Earth.

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Uneven Heating

• Causes some air to be hotter than other air.
• Hot air rises and the cold air falls which leads
  to the movement of the atmosphere.

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Local Winds

• Air is always moving.
• Local wind results from a local difference in
  temperature.
• Local winds often occur at lakeshores or
  seashores.
• Move short distances

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Prevailing Winds

• Global winds that always blow in the same
  direction.
• Caused by uneven heating of large places on Earth
  and Earths rotation.

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The Water Cycle

• Water is always moving.
• The water cycle is the movement of water between
  the atmosphere, land, and the ocean.
• Its important because everything on Earth
  depends on water.

• During evaporation water changes from a liquid to
  a gas.
• During condensation water changes from a gas to a
  liquid.

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The Water Cycle
8
The Water Cycle
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Clouds Precipitation

• The amount of water vapor in the air is called
  humidity.
• The first step in the formation of a cloud is
  water vapor condensing in tiny dust particles in
  air.

• When water drops are too heavy to stay in the
  atmosphere they fall from the sky in the form of
  precipitation.
• Rain is the liquid form of precipitation. Snow,
  sleet, and hail are solid.

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Types of Clouds

• Cumulus clouds are puffy. They indicate fair
  weather but a storm could grow.
• Stratus clouds from low in the atmosphere. They
  usually cover the sky.

• Cirrus clouds are high in the atmosphere. They
  are made mostly of air crystals.

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Measuring Weather

• Thermometer measures air temperature.
• Hygrometer measures humidity which is the amount
  of water in the air.
• Barometer measures air pressure.

• Anemometer measures wind speed.
• Windsocks measures wind direction.
• Wind Vanes measures wind direction.

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Measuring Weather

• Air temperature air pressure are related.
• A rising barometer shows increasing air pressure.
• Changes in wind often bring changes in weather.
• Weather can be predicted by observing the sky.
• Temperature and precipitation largely determine a
  regions climate.

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Air Masses

• A large body of air that has the same temperature
  and humidity.
• The name of an air mass indicates where it was
  formed.
• They can be warm, cold, humid or dry depending on
  where they formed.
• When weather changes in an area the air mass over
  that area is changing.

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Front

• The border where two air masses meet.
• Where most weather changes occur.
• 2 main kinds of fronts a cold front and a warm
  front

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Fronts

• Cold Front
• Forms where cold air moves under a warm air mass.
• Heavy rains or snow that doesnt last long.

• Warm front
• Forms where a warm air mass moves over a cold air
  mass.
• Rain of snow that can last for hours.

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Weather Patterns and Climates

• Weather in most places occurs in patterns.
• There are wind and temperature patterns.
• There are daily and seasonal patterns.
• Climate is the pattern of weather an area
  experiences over many years.

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Factors Affect Climate

• Areas location on a continent.
• Proximity to the equator.
• Proximity to a large body of water.
• Whether its in a rain shadow. (A rain shadow
  causes one side of a mountain to have a wet
  climate and other to have a dry climate.)

• Water heats more slowly than land because land
  quickly absorbs the suns energy as compared to
  water.

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Video
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Questions

• What causes weather?
• What conditions affect the water cycle?
• How can patterns in weather be observed?
• How does air temperature relate to water vapor?
• What happens to water vapor as temperature
  increases? Drops?