Temperature effects: cold air is more dense (heavier) than warm air, for the same volume, so has higher surface pressure, to get the same surface pressure, requires a smaller volume of cold air, warm air aloft is associated with high Pressure, and high cold air indicates low Pressure
Forces: pressure gradient - causes wind to blow, blows from high P to low P (perpendicular to isobars), steep gradient - strong wind, gentle gradient - weak breeze; coriolis force(shoot from train), deflect wind to the right in N. hemisphere, left in S. hemisphere, amount of deflection increases with increased velocity, amount of deflection increases toward the poles; surface friction, only affects velocity of near surface winds
Major Wind patterns:
Geostrophic winds, balance pressure gradient forces and coriolis
forces, high elevation winds blow in a straight path parallel to isobars;
Cyclones, Low pressure in center, ccw
in N; cw in S; Anti-cyclones , High
pressure in center
cw in N; ccw in S
Surface wind patterns: frictional force is added , friction slows wind so reduces Coriolis force, resulting wind blow across isobars toward low pressure (about 30º angle)
What are isobars? How can you determine the pressure gradient by looking at the isobars? Why is pressure usually shown on constant height maps?
Explain how pressure gradient and coriolis effect determine the direction of wind. What factors increase the intensity of each of these effects?
Why is surface friction only effective at low levels in the atmosphere? What is its effect on the wind?
Describe the surface and upper level wind patterns around a cyclone and an anti-cyclone. How and why are they different?