An atoll cloud forming over an island due to heating of the land during the daytime would be which type? （）

单项选择题Advection fog is most commonly caused by（）.

A.air being warmed above the dew point
B.saturation of cold air by rain
C.a rapid cooling of the air near the surface of the Earth at night
D.warm moist air being blown over a colder surface

单项选择题Advection fog holds longest over which portions of the lakes? （）

A.Northwest
B.Southeast
C.Northeast
D.Southwest

单项选择题According to Buys Ballot’s law，when an observer in the Northern Hemisphere experiences a northwest wind，the center of low pressure is located to the（）.

A.northeast
B.west-southwest
C.northwest
D.south-southeast

单项选择题A warm air mass is characterized by（）.

A.stability
B.instability
C.gusty winds
D.good visibility

单项选择题A series of brief showers accompanied by strong，shifting winds may occur along or some distance ahead of a(n)（）.

A.upper front aloft
B.cyclone
C.occluded front
D.cold front