Erosion and Wind

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Erosion and Wind
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Erosion

• Plate tectonics are not the only forces
• transforming the Earths landscape.
• Another such force is erosion

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• Erosion is the wearing away of rocks and soil
• by water, wind and certain human activities.
• Erosion results in the flattening of landforms.

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• There are three stages of erosion
• Weathering Fragmenting (breaking down) of the
  surface rocks.
• Transportation Rock fragments are carried by
  runoff water and wind. Erosion is compounded by
  the abrasive power of fragments transported by
  the water.

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• Sedimentation The fragments suspended in the
  water, or transported by glaciers or wind,
  accumulate and are compacted at the bottom of the
  oceans. They also accumulate in valleys and
  plains.
• Plants can help slow down the process their
  roots hold the soil in place. This can also
  prevent landslides.

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• In addition there are three categories of
  erosion
• Biological caused by living organisms. Ex
  decomposition of living things can create an
  acid which attack rocks. Ex Tree roots
  infiltrate rocks and ultimately break them down.
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• Mechanical caused by variations in
  temperature, pressure, wind, and water Ex Niagara
  Falls which recedes 3 m every year because the
  water wears down the rock.

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• Chemical Erosion Rain can become acidic
  because of pollutants and it chemically changes
  certain minerals in the soil such as limestone.
  This process gradually destroys rocks. Ex Acid
  rain can alter the surface of public statues.
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Wind

• Prevailing winds are not distributed evenly over
  the Earths surface. Two factors explain their
  particular distribution Convection cells and
  Coriolis Effect

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• 1. Convection cells when air warms up, it
  increases in volume and rises. This creates a
  low-pressure area on the ground below it. Colder
  air thus rushes in to replace the air that has
  risen.

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• The warm air moves and is cooled, bringing it
  down to the surface again. The hot air mass and
  the cold air mass are constantly in motion. The
  looping movements are called convection cells.
  See page 338 for diagram. On a smaller scale,
  convection is used as a means to heat houses.

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• 2. Coriolis Effect as the Earth rotates
  from west to east, it diverts air masses in the
  atmosphere to the right (Northern Hemisphere) or
  to the left (Southern Hemisphere). This is
  called the Coriolis Effect.

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• This movement produces the trade winds
  (equator and tropics), prevailing west wind
  (middle latitudes), and polar east wind (polar
  regions)