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Clouds and Fog


									Clouds and

  13.11 pg. 530-534
Energy in the Water Cycle

 Water in the hydrosphere picks up energy from
  the Sun.

 This causes the water to vaporize and to rise high
  in the atmosphere where the pressure and
  temperature drops.

 As a result condensation occurs and
  precipitation forms
        How Clouds Form

 There are three main categories of cloud
   Convective clouds
   Frontal clouds
   Orographic clouds
Convective Clouds

           Convective clouds: air near
            the ground picks up energy
            from the ground, warms and
            rises carrying vapor with it. It
            expands and cools as it rises
            into the cool, low pressure
            region of the atmosphere.
            This usually occurs wherever
            solar energy is absorbed by
            water and other surfaces
                Frontal Clouds

 Frontal clouds: Form
  when the leading edge
  or front of an air mass
  meets another at
  different temperature.
  This happens if a warm
  air mass moves over a
  cold one or if a cold air
  mass pushes under a
  warm one.
Orographic Clouds
             Orographic clouds:
              Forms when air
              moves up a
              mountain, expands
              at low pressure and
              cools. (“oro” comes
              from the Greek oros
              meaning mountain)

             Moisture in the rising
              air condenses in the
              colder air as it goes
              up the mountain,
              producing clouds

 Actually a cloud that forms near the ground.

 Fog commonly forms:
   On clear nights when energy radiates upward and
    is not reflected back
   When warm air passes over snow covered ground
   When moist sea air drifts over a cold current
    (coastal regions)
   When moist air rises up mountains during
    orographic lifting
         Classifying Clouds

 Classified in three ways:
   1.General Shape
      Cumulus (‘heap’) Clouds- have a billowing, rounded
        shape. Grow vertically, mean unstable weather. Form
        from convection currents, orographic lifting or when
        a cold air front pushes into a warm air mass

      Stratus (‘spread out’) Clouds- flattened and
        layered,grow horizontally, stable conditons, form
        when warm air mass overruns a cold one
      Classifying Clouds

 2.Altitude
   Low level- usually called stratus or cumulus
   Medium level- start with alto meaning higher
   High level- starting with cirrus (‘curly lock of hair’) are
     the highest
 3.Rain-holding:
   Nimbus-a rain holding cloud

   Name the 10 different types of clouds (see pg. 533)

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