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What is a gyre?
current flow around the periphery of ocean basins.
subdivided into currents by flow characteristic and temperature
make up about 10% of total ocean water
Wind driven by friction but divert due to coreolis effect (to the right in NH)
In NH surface current is deflected to the right of wind direction due to Coriolis effect.
2nd layer of water below it has friction from the upper water and moves to the right of that but slower speed
3rd layer down moves to the right of the 2nd layer and slower
4th to the right of the 3rd and slower
**theoretical net flow is 90d to the right of wind direction
***actual barely reaches 45d due to 'hills' and down pressure gradient.
****is effective down to 100m
ekamn transport and continues right deflection of water due to coriolis pushes water into in a hill.
water slides down hill due to gravity, cant turn left due to coreiolis so it continues right
this creates the conection of currents- gyres
the hill of water also dreates a greature pressure which depress the pycnocline much further below
6 major gyres of the world
- N-atlantic...to the right-clockwise
- N-pacific....." "
- S. Pacific
- S. atlantic
- Indian ocean........all to the left-counter clockwise
- antartic circumpolar current...west wind drift...alll the way around the pole frow west to east.
- ***tech not a gyre as iot doesnt flow around the pheripheral of a basin
types of currents within a gyre
- western boundry current -
- *fastest and deepest of gyre currents
- *west edge of ocean=east coast of land
- *move warm water poleward
- *ex: the gulf stream
- Eastern Boundry current-
- *east edge of basin=west edge of land
- *basicly the opp of western
- *cold water equataord
- *shallow and broad and slow
- transverse currents-
- *both eastern and western boundry tend to hug the shore.
- *transverse are the ones that cross the ocean.
- *broad and slow
caused when warm or cold water splits off a current.
in NH warm water goes right-anticyclonic
cold water goes to the left-cyclonic
- **eddies can be huge, up to 1,000km
- and retain their identity for 3 years!!!
why are the hills centers to the west?
why westward intensification?
the coriolis is stronger towards the poles. so east bound water in the N.Atlantic turns to the right (eqautor bound) faster.
this creates a wide broad mass of water moving southward which shoves the hill center to the west.
thus the westward current has less room forcing it faster and deeper.(same reason small narrow inlets have a faster tidal current)
counter currents and under currents-
equatorial current are accompanied by counter currents/undercurrents
- flow in opposite direction of main current
- due to lack of winds at the meteriological equator (5-8d north of geo).
the movement of water due to density
density is determined either by presure or salinity
where is density stratifaction highest?
near temperate/tropical areas because the temp difference between warm surface and cold bottom is the most extreme
at the poles both depp and surface water is closer in temp thus easier to mix.
what is caballing?
mixing of two massses of water with equal density but opposite temperature and salinity.
creates a denser mass of water that sinks
antartic formation of deep water/downdwelling
most significant is at antartica
ice production and cold temp produces densist water in the world.
it sinks, moves out along the continetal shelf and creeps northward
1000 years to travel along bottom to eqautor.
north artic formation of deep water/downwelling
similar to antartic however the basin of north atlantic restricts movement.
only place it can really get out is in the deep submarine canyons between scotland and green land
cold nnorth atlantic water plus the warm gulfstream and cold canadian wind releases heat making the warm temp. of n. europe
other deep waters
caused by extreme evaporation
mediteranian and enters through the straight of gibralter.
water is more salty then either artic but much warmer so it floats above the artic bottoms
Sun is the driving force of weather...
what effects how much is accepted into earth?
- Daily by rotation of the planet
- seasonaly by the tilt
- the angle at which the light hits the earth
- *90 degress more intense
- **>90 surface area is increased this not as direct.
- ***also amount of atmosphere it goes throught
what is the noon sun angle...how does it change?
The angle at which the sun hits earth at noone for a specific latitude
- sin(nsa)*100 = % intensity
what is the solar constant?
- the rate that energy from sun reaches earth
- 1388 watts/sq.meter
difference between weather and climate?
weather describes short period of time and is constantly changing.
Climate long term generalized statistics of weather
composition of the atmoshpere (4 main)
- N2 78%
- O2 21.5%
- Ar 1%
- CO2 .5%
- *all others trace elemets
where is ozone (the good ozone)
- in stratospher (2nd up )
- ~10-50km above surface
pressure decreases with altitude name two interesting facts about its concentration
- 1/2 atmospher is below 5.6 km
- 9/10 atmosphere is below 16km
atmosphere boundrys vs ocean water boundrys
atmosphere upper boundry denoted pause
- ocean water denoted -clyne
mean temp of earth without green houses gasses
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