Lenard effect

From Glossary of Meteorology
Revision as of 14:35, 20 February 2012 by imported>Perlwikibot
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)



Lenard effect

(Also called spray electrification, waterfall effect.) The separation of electric charges accompanying the aerodynamic breakup of water drops, first studied systematically by the German physicist P. Lenard (1892).

Experiments have shown that the degree of charge separation in spray processes depends upon the drop temperature, presence of dissolved impurities, speed of the impinging air blast, and contact with foreign surfaces. The largest fragments of the broken drops are observed to carry positive charges and the fine spray of drops carried off in the impinging air current carries a net negative charge. Distilled water drops of 4-mm diameter, broken after a 5-cm free fall into an updraft of 1 m s-1, were found by Chapman (1953) to yield about 10-10 C of separated charge per drop. The Lenard effect was incorporated by Simpson (1927) into his breaking-drop theory of thunderstorm charge generation, but many critical details are but poorly understood.

Chapman, S. 1953. Thunderstorm Electricity. Byers, H. R., ed., . 207–213.

Simpson, G. C. 1927. The mechanism of a thunderstorm. Proc. Roy. Soc. A. 114. 376–401.

Lenard, P. 1892. Über die Elektrizität der Wasserfälle. Ann. Phys., Lpz. 46. 584–636.


Copyright 2022 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.