Evanescent level

From Glossary of Meteorology



evanescent level

A theoretical boundary between a region in the fluid where waves of some frequency are propagating and a region in the fluid where waves of the same frequency do not propagate (where they are evanescent).

This is
also called a critical level but is distinct from the critical level where the background flow has the same speed as the phase speed of the waves.


Copyright 2024 American Meteorological Society (AMS). For permission to reuse any portion of this work, please contact permissions@ametsoc.org. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act (17 U.S. Code § 107) or that satisfies the conditions specified in Section 108 of the U.S.Copyright Act (17 USC § 108) does not require AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, require written permission or a license from AMS. Additional details are provided in the AMS Copyright Policy statement.