Atmospheric Pressure and Winds — Question 7
Back to all questions(i) The rotation of the earth produces another force other than the pressure force which is called the Coriolis force. It causes deflection of winds. Thus, the winds are directed to the right of their flow in the Northern Hemisphere due to Coriolis effect.
(ii) Temperature and pressure are inversely related to one another as atmospheric pressure decreases with increase in temperature. This is because when the temperature rises, air expands. The molecules of air move far apart and hence exert less pressure. On the contrary, with decrease in temperature, the air gets compressed and the space between molecules decreases and exerts more pressure on the region.
(iii) Humid air is lighter than dry air because the molecular weight of water is less than the average molecular weight of air. When water evaporates and enters the atmosphere as a gas, the water vapour molecules take the place of other gas molecules in the air. So, the volume of wet air weighs less than an equal volume of dry air.