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THE MOISTURE OF THE AIR: FOG AND CLOUD
A bank of cirro-stratus clouds in the west is apt to be the advance of a cyclonic storm. By the time the advancing clouds have reached the eastern sky, the storm is close at hand. Undulated alto-stratus clouds form under the
Ellerman, photo.
Thin, undulated alto-stratus forming above a fog, or stratus, Mount Wilson, Cal.
cirrus haze and these very shortly develop into rain clouds, or else are followed by them. A winter cyclonic storm may be likened to a cone with its apex tipped one hundred miles or more beyond its base.
