The direction of prevailing winds in the Northern hemisphere is caused by the（）.

A.Coming cold weather conditions
B.A warm front weather condition
C.High pressure conditions
D.Scattered cumulus cloudsduring the day

A.light，variable winds with little or no humidity
B.strong，gusty winds that blow from the same general direction all year
C.steady winds that reverse direction semiannually
D.strong，cyclonic winds that change direction to conform to the passage of an extreme low pressure system

A.forest fires
B.smoke from industrial areas
C.dust or sand storms
D.water droplets with the relative humidity more than 95%