The prevailing circulation of the atmosphere Polar ce‖l Polar front ce Horse Hadley latitudes Polar easterlies 60° subpolar low H Doldrums Subtropical high ≠·L 0 Intertropical convergence zone(ITCZ Equatorial M SE trade winds H H W Polar easterlies FIGURE 11.2 Diagram(a) shows the idealized wind and surface-pressure distribution over a uniformly water-covered rotating earth Diagram(b)gives the names of surface winds and pressure systems over a uniformly water-covered rotating earth
The prevailing circulation of the atmosphere
HADLEY CELLS ARE THERMALLY DIRECT CIRCULATIONS As are( weak) polar cells 30 60 Latitude LOW LOW High LOW rface Pressure Systems FERREL CELLS ARE THERMALLY-NDIRECT CIRCULATIONS
60 30 0 30 60 N S Latitude Low High High Low Surface Pressure Systems HADLEY CELLS ARE THERMALLY DIRECT CIRCULATIONS FERREL CELLS ARE THERMALLY-INDIRECT CIRCULATIONS As are (weak) polar cells Low
Polar high Subpolar lows Subtropical highs Precipitation occurs in bands ITCZ Equatorial low surface convergence (low pressure regions) Subtropical highs 30° Subpolar lows 45° Polar high FIGURE 11.5 Major pressure systems and idealized air motions (heavy blue arrows)and precipitation patterns of the general circulation (Areas shaded light blue represent abundant rainfall
Precipitation occurs in bands of surface convergence (low pressure regions)
Atmospheric vertical circulation S 60 30 0 Latitude Surface Pressure centers L High Wester ⊥1| Easterly Surface Winds
60 30 0 30 60 N S Low Latitude Low High High Low Atmospheric Vertical Circulation Surface Pressure Centers 60 30 0 30 60 N S Westerly Easterly Surface Winds
Geostrophic Balance: Responsible for east-west component of wind at surface 2Vsin=(1/p)△p/△ Polar cell Polar high Polar front △p/△y<0→V>0 Ferrel cell Horse Hadley (westerlies) H △p/△y>0→<0 (easterlies) At the equator there are weak easterlies(doldrums)
2WVg sin f= -(1/r) Dp/ Dy Geostrophic Balance: Responsible for east-west component of wind at surface Dp/ Dy>0 → Vg <0 (easterlies) Dp/ Dy<0 → Vg >0 (westerlies) At the equator there are weak easterlies (“doldrums”)