The doldrums are characterized by（）.

单项选择题The direction of prevailing winds in the Northern hemisphere is caused by the（）.

A.Magnetic field at the North Pole
B.Gulf Stream
C.Earth's rotation
D.Arctic cold fronts

单项选择题Steady precipitation is typical of（）．

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

单项选择题Monsoons are characterized by（）.

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

单项选择题MIST is caused by（）.

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

单项选择题In the Southern Hemisphere winds in a low pressure system rotate in a（）.

A.clockwise direction
B.northeasterly direction
C.northerly direction
D.counterclockwise direction