Ball electricity
As Balloelektrizität or as Lenard effect , commonly known as the Waterfall -electricity is called the apparent negative charge of the air during nebulization of water drops.
As Alessandro Volta already noted, the atomized water droplets of a waterfall are negatively charged due to a charge separation when the water droplets are atomized .
The term "Lenard effect" refers to the later Nobel laureate in physics in 1905, Philipp Lenard , who examined this effect in a wind tunnel around 1890 and addressed it in his habilitation thesis "On the electricity of waterfalls" ( University of Bonn , 1892). The term "ball electricity" was coined in 1913 by the Danish physicist Christian Christiansen ; it was derived from the ballista , a Greek or Roman stone throwing machine. Sydney Chapman , for example, carried out other experiments that showed a small charge of water droplets when falling in a updraft .
Explanation of the effect
According to Lenard, the water droplets are polarized by molecular interaction with the surrounding air: negative charges accumulate on the surface, positive charges inside. Upon impact, the surface is torn off and atomized as small droplets that are released into the air while the positively charged main droplet dissolves.
Substances dissolved in the liquid can strongly influence this effect and even reverse the sign. Ballelectricity occurs not only in water droplets, but is also observed in other liquids .
GC Simpson used the effect in 1927 to explain the generation of charges in thunderstorms . During thunderstorms, however, the formation of ice plays an important role (see causes of lightning ).
literature
- Alfred Coehn : waterfall electricity . In: Wilhelm Westphal (Hrsg.): Handbuch der Physik . Volume 13, 1928
Web links
- Lenard Effect . In: Glossary of Meteorology (English)
Individual evidence
- ^ Geissler's tube (explanation of the phenomena) . In: Meyers Konversations-Lexikon . 4th edition. Volume 7, Verlag des Bibliographisches Institut, Leipzig / Vienna 1885–1892, p. 32.
- ↑ Lenard: About the electricity of the waterfalls . In: Annalen der Physik , Volume 46, 1892, pp. 584-636
- ↑ Christiansen, Christian: Electricity excitation when liquids are sprayed (ball electricity) . In: Annalen der Physik , Volume 345, 1913, pp. 107-137 & 233-248
- ^ S. Chapman: Thunderstorm Electricity 1953
- ^ Wilhelm H. Westphal, Walter Westphal: Physics . Springer, 1970.
- ^ GC Simpson: The mechanism of thunderstorms . In: Proceedings Royal Society A, Volume 114, 1927, pp. 376-401