Meda Davison, age 15, of Mooresville, N.C., for her question:

WHY ARE RAINBOWS CURVED?

You will see a rainbow as an arc when the sun is behind you and the sky in front of you is filled with moisture. Your location to the sun's position determines the curve. Each band of color occurs at a certain angle. In the red band of color, all the points of the arc measure 42 degrees from the line formed by the sun's rays. The other colored bands occur at angles less than 42 degrees from the sun's rays.

The higher the sun, the lower the bow. If the sun rises higher than 40 degrees, no bow can be seen. When the sun is near the horizon, an observer on a high mountain might be able to see the whole circle of the rainbow.

Sometimes light from the moon can form a rainbow. The rainbow differs from the sun's only in intensity of color, with the lunar rainbow usually being very faint.