From Glossary of Meteorology
Revision as of 18:10, 25 April 2012 by
(Also called upper trough, upper-air trough, high-level trough, trough aloft.) A pressure trough existing in the upper air.
This term is sometimes restricted to those troughs that are much more pronounced aloft than near the earth's surface. These troughs are often described as either short-wave or long-wave features.