Currents and Climate

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Currents and Climate
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Currents and Climate

• There are two types of currents
• Surface
• Density

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Surface Currents

• Affect only water to a depth of 100m
• Are cold or warm depending on their starting
  location.
• Caused by the wind
• Due to the spinning of the Earth the currents in
  the Northern Hemisphere curve to the right
  (clockwise), and in the Southern Hemisphere curve
  to the left (counter clockwise). This factor is
  called the Coriolis Effect.

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Surface Currents
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Currents and Climate

• As the currents in the oceans move past the
  continents, they affect the climate on land.
• The Gulf Stream brings warm water to areas in the
  North Atlantic that should not be that warm.
  (British Isles, Iceland)
• Cold Currents in the Pacific make the ocean off
  the Wash./Oregon coast extremely cold, even in
  the summer.

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Density Currents

• These are deep currents that cause water to creep
  along the bottom of the ocean floor.
• The cold waters near the poles, sinks to the
  bottom while the warm tropical waters near the
  equator bring the water to the surface
• These currents move and mix the water around the
  planet. It may take 1000 years for the water at
  the poles to move to the equator.

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Density Currents (Deep water Current)
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Deep water current (side view)
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Upwellings

• Sometimes very fast moving winds or a storm will
  push away the top layers of the water. (Very
  small isolated areas.)
• This allows the cold, nutrient rich water near
  the bottom to reach the surface.
• The fish flock to that area because of the high
  nutrient content, and it makes for great fishing
  !!!

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Tides

• Tides are caused by the interaction of the sun,
  moon, and the Earth.
• Gravity is pulling the Earth towards the moon and
  towards the Sun. Its what keeps us in our orbit!
• That pull of gravity, causes the water on the
  Earth to be pulled further in one direction at
  different times of the month.

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Daily Tides

• Every day there are high tides and low tides. At
  the Jersey Shore, there are 2 high tides and 2
  low tides every day.
• Why would it be important to know the times of
  these tides?

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Semidiurnal tides

• As the earth turns upon its own axis in about 24
  hours, a point on the earth moves through areas
  with these different forces acting on it. In one
  rotation (one day), a point on earth travels from
  an area of high tide (where there is a force
  pulling water outward), through an area of low
  tide, through and area of high tide again (the
  opposite pull), and through another area of low
  tide, before it returns to the point of origin at
  high tide. This results in two high tides and two
  low tides in a day (called semidiurnal tides).

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Monthly tides

• The changes of the alignment of the Earth, Sun
  and the Moon will cause the tides to be greater
  than normal or lower than normal.
• There are two types of monthly Tides Spring
  Tides and Neap Tides

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Tides
Spring Tide
Neap Tide
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Tidal Range

• The tidal range is the measured distance between
  the high tide and the low tide.

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Spring Tides

• The Sun, the Moon, and the Earth are all in a
  straight line.
• Results in the highest high tides, and the lowest
  low tides (twice a month)
• Greatest tidal range during the month

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Neap Tides

• The Sun, the Moon, and the Earth are at right
  angles to each other
• That makes the lowest high tides and the highest
  low tides
• The Tidal Range is the smallest