Laws of horizontal motion.
1.Pressure gradient force 2.Coriolis force 3.Centripetal force 4.Frictional force These 4 factors affect the wind. The wind speed is a product of the balance of these forces.There will always be areas of high pressure and areas of low pressure. Fact that pressure varies on the earth’s surface. Difference in pressure can have 2 causes; thermal/heating affect (amazon rainforest, intense heating gives low pressure along the equator). Mechanically by the wind.Mean sea level pressure chart – isobars; joins together locations of equal atmospheric pressure.
1.Pressure gradient is the change in pressure divided by the distance of 2 points. dp/dn = change in pressure / horizontal distance (pascal per metre) Movement from high pressure to low pressure.Calculating the pressure gradient force from the pressure gradient. This contains rho, the air density. PGF = -1/p x dp/dn (- sign as air is blowing from high to low pressure) 1mb = 100Pa At rho increases, PGF decreases. Pressure changes faster, then it will be windier.Do question sheet.
2.Coriolis force is due to the earth’s rotation on air movement.The deflective force per unit mass is; f = 2wvsin(theta) F = Coriolis force W = angular velocity of the earth Must be in RADIANS
- radian = 57.3
o
360 o = 2pi radians So, 6.28 radians = 360 o W = 2pi / (60x60x24) = 7.2722 x 10 -5 rad/s V = velocity of the mass Theta = latitude Sin0 = 0 (equator)
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