Dear Dr. Boli: Why are there so many different kinds of clouds? Shouldn’t they be rationalized? —Sincerely, J. Bhatia, President, American National Standards Institute.

Dear Sir: Clouds are wilful and capricious beings, of a decidedly libertarian bent, and resist all efforts to regiment them into a more rational order. The best that can be done, therefore, is to learn the various types, so as to be able to distinguish between clouds that intend merely to get you a bit wet and clouds bent on knocking down your house.

Cumulus.—Cumulus clouds are the puffy white clouds one sees in the sky on an otherwise fair day. The most up-to-date meteorological theory suggests that cumulus clouds are the souls of departed lambs and kittens.

Nimbus.—Nimbus, or rain-bearing, clouds are the shadows cast by cumulus clouds on the other side of the earth.

Cumulonimbus.—When, owing to a sudden lurching about of the atmosphere, cumulus clouds come into contact with their shadows, the nimbus clouds, the result is a towering rage. This is a lesson to us all.

Funnel.—Funnel clouds are conduits, somewhat like large garden hoses, through which the wrath of heaven is conveyed to earth.

Cirrus.—Cirrus clouds are not truly clouds at all, but rather an optical illusion caused by staring into the bright sky too long.

Stratus.—These are the featureless grey clouds one sees on a cloudy day. Their primary function is to obscure the heavens so that more destructive species of cloud can sneak up on us.

Tag.—These consist of a large number of printed words, some larger and some smaller. Tag clouds are an increasingly common, though still striking, meteorological phenomenon; their surprising prevalence of late is attributed by some climatologists to global warming. Other scientists, however, suggest that tag clouds may be the chief cause of global warming.