Atmospheric Circulation and Wind Flashcards
What is the idea behind general circulation?
- More direct sunlight at equator causes greater warming and rising of air, replaced by cooler air further from the equator.
- Results in a general circulation pattern.
What are the 3 cells in the 3 Cell Model of global circulation?
- Polar Cell
- Mid Latitude Cell
- Tropical Cell
What causes the formation of the 3 cells?
Coriolis force
What direction does the Coriolis force tend to deflect particles in the Southern Hemisphere? What about Northern Hemisphere?
- To the left in SH
- To the right in NH
What is the Coriolis force an apparent force?
Because the deflection is relative to the observer not relative to the particle’s movement through space
What causes the Coriolis force?
Rotation of the earth.
What is Coriolis force proportional to?
- Wind Speed
2. Latitude (zero at the equator, maximum at the poles).
What is the pressure gradient force?
Movement of air from HP to LP
On a synoptic chart, what do isobars being close together mean?
Represent a large change in pressure over a small distance
- Pressure difference will be high
- PGF will be high
- Speed of the wind will be high
On a synoptic chart, what do isobars far apart mean?
Small change in pressure over a large distance
- The PGF will be low
- The Wind speed will also be low
What direction do winds flow on an synoptic chart?
Parallel to isobars
What is geostrophic wind?
Balanced flow between Coriolis force and pressure gradient force
- Flow will be parallel to the isobars.
What causes the predicted geostrophic flow away from being parallel to the isobars slightly at the surface?
Friction
What direction does air flow around an area of high pressure in the southern hemisphere?
Anti-clockwise
What direction does air flow around an area of low pressure in the southern hemisphere?
Clockwise
What are the 2 main jet streams and where do they occur?
- Subtropical Jet - forms near the boundary of the Tropical and Mid Latitude circulation cells
- Polar Jet - Forms near the boundary of the Polar Cell and Mid Latitude Cell
What direction do the jet streams flow in the southern hemisphere and northern hemisphere?
West to East
What is Buys Ballot Law?
In the Southern Hemisphere, if an observer stands with his back to the wing, pressure is higher on his left hand than his right.
What is the explanation for jet streams?
The trapping of upward air by the tropopause layer, force the air to move toward the poles and as it does, the effect of Coriolis deflecting the air and the acceleration due to conversation of angular momentum creates the jet stream.
Which side of the jet streams is turbulence likely to be greater?
Polar side
