Valerie McDonald, age 12, of Merritt, B.C., Canada, for her question:

Is it true that frogs rain down from the sky?

This sort of thing has been reported many times. Once in a while a few people insisted that a storm brought a shower of baby frogs down with the raindrops. But experts pooh poohed the story and said it was impossible. They did so, too, when showers of small fishes, crabs and periwinkles were reported. But now we know more about the mighty forces of the atmosphere    and it doesn't seem quite so farfetched to believe that a shower of frogs is possible.

The average frog can expect to spend his merry life in and around his personal pond or stream. He hatches from a jellified egg in a mass of floating frog spawn and spends his kindergarten days as a fishy tadpole. Later, he swaps his gills for lungs, absorbs his tail and progresses to froghood in easy stages. Certainly, he rightfully belongs on the surface of the earth and nothing in the program suggests a trip aloft into the clouds.

Considering these proveable facts, no wonder the experts refused to believe that frogs shower down from the sky. But in 1881, the town of Worcester in England was struck by a rather fierce storm. Reliable witnesses insisted that crabs and periwinkles came down with the rain. Another report was of a thunderstrom that dropped squirming fishes near Providence, Rhode Island. And showers of frogs have been reported from other places.

The problem, of course, is how these smallish creatures got up into the clouds in the first place if, indeed, they did. We know now that our caeathery atmosphere is a stupendous engine that can hoist aloft millions of tons of moisture by evaporation. But, of course, it can't evaporate a frog or a crab or a periwinkle in the same way.

A much more violent process, an extremely powerful updraft of air, would be necessary to lift up something as big as the smallest frog. But once something this big was lifted into the raging winds inside thunder clouds, it is possible that it could be carried some distance before it came plopping down to earth again. However, though we can believe it possible that frogs have fallen from the sky, so far no reliable scientists have been on the spot to prove it has really happened.

Ecologists have been investigating the clouds for other signs of life. And sure enough, they have found various species of microscopic plants and animals small enough to stay aloft among the misty droplets of cloud moisture. They thrive there and multiply during the short life of the cloud.