Debbie Brown, age 16, of Trinity, N.C., for her question:

WHAT CAUSES SNOW BLINDNESS?

Snow blindness is a temporary loss of sight caused by bright sunlight reflected from snow.  It usually lasts from several days to a week.

Sometimes a person has trouble distinguishing between colors after he has had snow blindness. Often he will continue to see red for a long time.

Snow blindness disappears when a person rests his eyes and remains indoors.

Wearing dark colored glasses helps avoid snow blindness. Eskimos living in the Arctic areas avoid the problem by wearing goggle like bone shields with long, narrow slits over their eyes.

Snow, by the way, always appears as tiny six sided crystals with no two crystals exactly alike.