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Earth 002
Monday, February 4th, 1999
Announcements: The second homework
assignment was given in class today. It is due next Tuesday at
the beginning of class.
Lecture notes:
OCEAN CIRCULATION
- Organisms in the ocean's surface absorb energy, and then
it is reflected in the top 200 emters of the water
- The top 200 meters are known as the Photic
Zone--the zone of life
- At higher elevation, there is greater reflection
ENERGY IMBALANCE
- More energy is input at the tropics than is input at the
poles
- More energy is output at the poles than at the equator
- Because of this, the ocean must be circulating and moving
water from the poles to the equator and vice versa in
order to prevent energy imbalance
WIND-DRIVEN CIRCULATION
- Created by wind blowing over the surface of the water
causing friction which leads to energy loss
- The top layer of molecules then sends the 2nd layer into
motion
- The wind blows to the right in the Northern Hemisphere;
to the left in the Southern Hemisphere (Known as Mass
Transport)
ECKMAN SPIRAL
- The wind does not push the water in front of it, it moves
the water to the right
- In the Eckman Spiral, the deeper you
get, the shorter the vector will be
UPWELLING
- Upwellings are divergences that occur
when water is moved offshore because water moves
rightward in the Northern Hemisphere
- Because of continuity, water must be brought up from down
below-->VERY HIGH PRODUCTIVITY
- Many nutrients are found in these areas because old
nutrients are constantly being replaced with new
nutrients from down below
- When winds diverge, water is pushed
downward causing water to converge
- When air converges, water from below is
forced upward causing water to diverge
TEMP-SALT DRIVEN
- Warm water is less dense, cool water is more dense
- Evaporation, precipitation, and rivers all govern the
water's salinity
- Less dense water sits on top of more dense water
SEA ICE
- Ice, which is made of extremely cold and dense H2O,
excludes salt. The salt that used to be in this water is
added back into the lower sea water
- Sea's such as the Weddell Sea fill the earth's oceans
with cold saline waters.
REVIEW
- There are two mechanisms by which the earth transports
heat: 1) Wind Driven Circulation and 2) Temp-Salt Driven
Circulation
- Ocean circulation changes dramatically. When a region is
covered with ice, there is no interaction.
TEST STUFF
- For the test next Thursday...know Mass Transport and
Eckman Spiral
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