atmospheric and oceanic circulations
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ATMOSPHERIC AND
OCEANIC CIRCULATIONS
1. Introduction
2. Mapping pressure variations
3. Causes of pressure variations
4. Driving forces within the atmosphere
5. General circulation of the atmosphere
6. Ocean currents
THIS HAPPENS AT LARGER
SCALES, TOO……..
Example 1: The Asian Monsoon
Example 2: The General Circulation of the
Atmosphere
The Asian monsoon: winter.
Source: Christopherson, 2003, p. 167.
Himalayas/Tibetan
Plateau (cold) HIGH
The Asian monsoon: summer.
Source: Christopherson, 2003, p. 167.
Himalayas/Tibetan
Plateau (warm) LOW
0°
(equator)
30°N 90°N
(north pole) 60°N 30°S 90°S
(south
pole)
60°S
WARM COLD COLD
Beginnings of the general circulation of the
atmosphere.
CAUTION: the reality is more complicated.
We’re not finished with this yet!
DRIVING FORCES WITHIN THE
ATMOSPHERE
1. Pressure gradient force
2. Coriolis force
3. Friction force
(4. Gravity)
Spiral movements
evident in wind
patterns over the
Pacific Ocean.
Source: Christopherson, 2009,
p. 148.
Deflection to the
right in the
northern
hemisphere
Deflection to the
left in the southern
hemisphere
No deflection at
all at the equator
Maximum deflection at the poles
Maximum deflection at the poles
POINTS TO REMEMBER ABOUT THE
CORIOLIS FORCE:
1.It is an apparent force that works to deflect
air to the RIGHT in the northern hemisphere,
LEFT in the southern hemisphere.
2. It always acts at 90° to the wind direction.
3. It is directly proportional to wind speed.
4. It is directly proportional to latitude.
HIGH
Geostrophic wind (no friction):
wind travels parallel to isobars,
without crossing them.
LOW
Northern hemisphere: wind deflected to the right
WINDS AT THE SURFACE
Importance of friction
1020 mb
1016 mb
1012 mb
1008 mb
HIGH
LOW
Pressure
gradient force
=
Coriolis force
Wind direction
HIGH LOW
Northern hemisphere: wind deflected to the right
Winds at the surface: wind crosses
isobars at an angle.
HIGH- CLOCKWISE LOW- COUNTER CLOCKWISE
0°
(equator)
30°N 90°N
(north pole) 60°N 30°S 90°S
(south
pole)
60°S
WARM COLD COLD
General circulation of the atmosphere- part II.
H H
Hadley cells
Subtropical high pressure cells
Polar front Polar front
JET
JET
JET
JET
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