217. Clouds appearing in the following order: cirrus, cirrostratus, altostratus, stratus, and nimbostratus usually indicate the approach of a(n) _______ .

An atoll cloud forming over an island due to heating of the land during the daytime would be which type? （） A: Cirrus B: Cumulus C: Stratus D: Nimbu

An<br/>"atoll cloud" forming over an island due to heating of the<br/>land during the daytime would be which type? () A: Cirrus B: Cumulus C: Stratus D: Nimbus