MEASURING RAINFALL WITH RADAR
Because of the importance of water in almost all aspects of human activity, people have been measuring and keeping records of rainfall for a long, long time. Fortunately. if someone is interested in knowing how much rain falls at a particular point, this information is easy to get. An ordinary bucket can serve as a rain gauge, provided it is set away from trees and buildings and account is taken of the taper of the sides of the bucket. As a matter of fact, most rainfall records in the archives of the weather observers around the world have been obtained with what might be considered glorified buckets.
The standard U. S. Weather Bureau rain gauge, as shown in Fig. 11 consists of a cylindrical vessel with an opening 8 inches in diameter. The captured rain water is funneled into a narrow inner cylinder. The amount of rain may be measured by dipping a stick in the water and reading a level mark, as you would check the oil in your car. The narrow cylinder has a cross-sectional area one-tenth the area of the opening through which the rain falls. When a stick dipped