LAND AND SEA BREEZES

The weather associated with the summer monsoon winds is thunderstorms, almost constant heavy rain, rain showers, and gusty surface winds. This condition is caused by mass motion of air from the relatively high-pressure area over the ocean to a low-pressure area over land. When the air leaves the ocean, it is warm and moist. As the air travels over land toward the low-pressure area, it is also traveling from a lower altitude to a higher altitude. The air is lifted by a mechanical force and cooled to its condensation point by this upslope motion (pseudo adiabatic process). LAND AND SEA BREEZES There is a diurnal (daily) contrast in the heating of local water and land areas similar to the seasonal variation of the monsoon. During the day, the land is warmer than the water area; at night the land area is cooler than the water area. A slight variation in pressure is caused by this temperature contrast. At night the wind blows from land to sea and is called a land breeze. During the day, the wind blows from water areas to land areas and is called a sea breeze. 3-22 RADIATION LAND COOLING AG5f0324 WARM OCEAN CONVECTION Cu Cu COOL AIR LAND OCEAN WARM AIR SEA BREEZE LAND BREEZE Figure 3-25.—Circulation of land and sea breezes.