Topic 10 Ice and Fog

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Topic 10Ice and Fog

• GEOL 2503
• Introduction to Oceanography

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Ice

• Ice is fresh water, pure H2O
• Dissolved materials are left behind in the
  surface water
• Remaining surface water has increased salinity
  (same amount of salt, less liquid water)

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Sea Ice
Frozen ocean surface water
Photos from the International Ice Patrol photo
gallery http//www.uscg.mil/lantarea/iip/Photo_Ga
llery/Category.shtml
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Land Ice

• Earth's ice cover formed on land as the result,
  principally, of the freezing of precipitation
• Takes water from one reservoir (ocean) and moves
  it to another (land)
• Changes the volume of water in oceans (and sea
  level)

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Ice Sheets

• Regional, extensive covering of land ice
• Antarcticlargest
• Greenlandsecond largest
• Sometimes referred to simply as glaciers, but
  there are also small glaciers in mountains and
  elsewhere that are not ice sheets

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More Ice Terms

• Fast Icesea ice anchored to land mass, doesnt
  move
• Ice Floesea ice not anchored, moves with
  currents
• Icebergbroken off chunks of land ice

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Icebergs

• Ice is about 10 less dense that liquid water
• So only about 10 floats above water
• tip of the iceberg

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Icebergs off Greenland
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• Iceberg photos from IIP
• Coast Guard plane
• Tabular iceberg
• Worlds tallest iceberg, 550 feet

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Notice the latitude at which the Titanic sank.
Since then, the sea surface has warmed enough
that today there are no icebergs south of about
45 degrees north latitude
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Fog

• Cloud at ground level
• Form when air cant hold all the water vapor
  (cool air cant hold as much as warm)
• Fog/clouds are liquid waterdroplets
• Three types
• Advective
• Radiative
• Sea Smoke

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Advective Fog

• Warm air, saturated with water vapor
• Moves over colder water
• Blanket of fog forms at surface of water
• Tends to persist
• Grand Banks
• San Francisco

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Radiative Fog

• Warm days, cold nights
• Earth surface cools at night
• So does air above surface
• Moisture in air condenses at night
• Forms low-lying, thick fog
• Dissipates as air warms, water evaporates
• Also called radiation fog

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Sea Smoke

• Dry, cold air
• Moves over warmer water
• Water warms air above it
• Air picks up moisture from water
• Warmed air rises rapidly
• Air cools, water vapor condenses
• Forms ribbons of fog

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How sea smoke forms
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