Kay Shackelford, age 12, of Jackson, Miss., for her question:

What causes the change in the color of the sea?

In small amounts, water seems to be transparent. In large amounts it has a bluefish cast and there is certainly a large amount of water in the sea. The shining face of the sea acts like a mirrors reflecting the color of the sky above. On clear days, this adds to its blue color. On cloudy days, the sea gets a grey color from the sky.

Sometimes the ocean water is loaded with microscopic plants which may be green, brown or red. Sometimes these microscopic plaints or animals give off a ghostly glow, adding a burnished phosphorescent gleam to the water. Near the shores, the shallow waters may stir up mud and sand from partly submerged shoals. All these factors play a part in the changing colors of the sea, but the basic colors came from the water itself and from the sky above.