Glossary of Meteorological Terms (J)

J

Jevons effect

The effect upon the measurement of rainfall caused by the presence of the rain gauge.

Jordan sunshine recorder

A sunshine recorder of the type in which the time scale is supplied by the motion of the sun. It consists of two opaque metal semi-cylinders mounted with their curved surfaces facing each other. Each of the semi-cylinders has a short narrow slit in its flat side. Sunlight entering the slits falls on light sensitive paper which lines the curved side of the semi-cylinder. One semi-cylinder covers morning hours, the other afternoon hours.

Joule

A unit of energy equal to 107 ergs or to 0.2389 calories. Named for British physicist James Prescott Joule (1818-1889).