单项选择题
A.cirrus B.cirrostratus C.altostratus D.cirrocumulus
Clouds are classified according to their（）.A.sizeB.mois...
单项选择题Clouds are classified according to their（）.
A.size B.moisture content C.altitude and how they were formed D.location in a front
Clouds appearing in the following order: cirrus，cirrost...
单项选择题Clouds appearing in the following order: cirrus，cirrostratus，altostratus，stratus，and nimbostratus usually indicate the approach of a(n)（）.
A.warm front B.occluded front C.medium front D.cold front
Cloud formations are minimal when the（）.A.surface tempe...
单项选择题Cloud formations are minimal when the（）.
A.surface temperature and temperature aloft are equal B.surface temperature and temperature aloft differ greatly C.barometric pressure is very low D.relative humidity is very high
