Winds related to regional and local air movements - monsoons and föhn winds Flashcards
What are monsoon and föhn winds?
these are regional wind that appear only at a certain time of the year and at a certain region
explain monsoon winds:
monsoon winds are seasonal winds that occur mainly in tropic regions, the most affected area is SE Asia particularly India.
in winter air north of the Himalaya mountains, at Siberian plateau become cold and cause Hp and areas surrounding warmer seas have Lp and the cold wind will travel from Hp to Lp and this brings dry, pleasant weather.
when this wind disappears in April to May temp rise rapidly above 35* C
in summer process reverses, Siberian plateau is now hotter than surrounding seas now air comes SW to India and brings very moist air and also drop in Temp that causes heavy downpours.
what does leeward mean?
the side of a mountain where winds descend and warm up
what does windward mean?
the side of a mountain where winds rise and cool down
what does lapse rate mean?
the rate which temperature changes in the atmosphere with change in altitude
what are föhn winds?
a warm, dry wind that descends the leeward side of a mountain
how are föhn winds formed?
when moist air rises windward it cools due to lapse rate, while air is unsaturated it cools at the dry adiabatic lapse rate of 1C per 100m once condensation begins the rising sir cools at the wet adiabatic lapse rate of about 0,5C per 100m .
this cooling causes water vapour, rain or snow on the windward side.
as air starts descending on the leeward side it warms up rapidly because there is now very little moisture and this is the föhn wind.
