Gary Townes, age 10 of Goodettsville, Tenn.., for his question:

How does the weatherman determine the ceiling?

The weatherman's ceiling is the base of the clouds when they cover more than half of the sky. ',.n experienced weatherman can estimate the height of the clouds fairly accurately, but more exact data is needed when it comes to the landing and launching of planes,

One method is to release a balloon which rises at a fixed rate. It takes so many seconds to rise so many feet. When it disappears in the clouds the weatherman's stop watch tells him the height of the ceiling. The clinometer is a more elaborate way to tell the height of the clouds. It requires a search beam pointed directly up am' an angled gadget with a lens. An observer stands 1,000 feet from the light and notes where it makes a. white patch on the cloud coiling. The clinometer gives an angle from this lookout spot and. the observer uses a chart to translate this angle into the height of the ceiling.

Large modern air ports have an automatic ceiling detector on duty at all times. It is a photo electric cell and, a vertical beam of light. The cell is aimed. at the light and it is constantly turning. It checks and rechecks the cloud. ceiling with every turn.