Collision efficiency

From Glossary of Meteorology
Revision as of 16:43, 26 January 2012 by imported>Perlwikibot (Created page with " {{TermHeader}} {{TermSearch}} <div class="termentry"> <div class="term"> == collision efficiency == </div> #<div class="definition"><div class="short_definition">The f...")
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

collision efficiency

  1. The fraction of all water drops in the path of a falling larger drop that make contact with the larger drop.

    Calculations using approximate drag forces between large and small cloud drops predict low collision efficiencies (<10%) when the large drop is less than 40 μm in diameter but collision efficiencies approaching 100% when the larger drop is greater than 80-μm diameter. Thus theory indicates that the collision–coalescence process for precipitation formation requires at least a small fraction of cloud drops to be larger than about 40-μm diameter. Because collision between drops does not necessarily result in coalescence, it is important to distinguish between collision efficiency and coalescence efficiency. Their product, termed the collection efficiency, gives the fraction of drops that collide and coalesce.
    See warm rain process.

  2. The fraction of drops or aerosol particles colliding with precipitation particles.

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