From Glossary of Meteorology


A cavum, or hole-punch cloud, is a large gap, usually circular or elliptical, that can appear in cirrocumulus or altocumulus clouds. These formations occur when part of a cloud with supercooled water droplets freezes into ice crystals owing to inadvertent seeding by aircraft flying through clouds at temperatures below about −10° to −20°C, even without sufficient ice nuclei, due to cooling as air expands over the wings or propellers.

Term updated 24 April 2017.

Copyright 2022 American Meteorological Society (AMS). For permission to reuse any portion of this work, please contact [email protected]. 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.