HOPKINS GLOSSARY OF WEATHER TERMS F
- The earth's atmosphere extending upward from above the planetary
boundary layer (or above altitudes ranging between 1-2 kilometers
above ground level), where effects of the earth's surface friction
upon air motion are negligible.
- The number of cycles or times that a periodic event occurs
during a fixed time interval; the reciprocal of the period
of the periodic phenomena. The dimension is reciprocal time,
or cycles per time, with the Hertz (Hz) (equal to 1 cycle
per second) defined as the standard unit of frequency. Frequency
is one of the ways used to identify wave phenomena.
Last update 6 June 1996
Edward J. Hopkins, Ph.D.
Department of Atmospheric and Oceanic Sciences
University of Wisconsin-Madison