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.
