Pressure Pressure Gradient Force Coriolis Force Horizontal Winds Pressure Pressure Gradient Force Coriolis Force

The Basic Pollution Problem Transport (wind vector and turbulence) Observed State Source (emissions) Transformation (chemical reaction) Effects Environment Health Environment (temp, RH,rad, chems)

What causes the pressure to change Is higher 50% mass level Same mean Temperature 50% mass level 50% mass level T in column 2 is greater Column 1 Column 2

Horizontal Pressure Gradient Force (HPGF) 500 mb 496 mb 492 mb ~300km isobar: line of constant pressure S W E

HPGF HPGF: due to the change in atmospheric pressure with distance. Magnitude of HPGF: if p changes rapdily with horizontal distance--> isobars are closer together and HPGF is large Effect of HPGF: air starts to move from H to L

Consider a hill Z distance When height (z) changes fastest over the same relative distance, the slope of the hill is greatest

Suppose the hill is pressure When the lines are closer together, the HPGF is greater!

Coriolis The wind does not blow directly from H to L

The Wind does not blow directly from H to L The Coriolis force causes an “apparent” deflection of the air to the right (left) in the Northern (Southern) Hemisphere

Geostrophic Wind

Gradient Wind

Winds near the surface