INVESTIGADORES
AVILA Eldo Edgardo
artículos
Título:
Measurements of electric charge separated during the formation of rime by the accretion of supercooled droplets
Autor/es:
LIGHEZZOLO R. A.; PEREYRA R. G.; AVILA E. E.
Revista:
ATMOSPHERIC CHEMISTRY AND PHYSICS
Editorial:
COPERNICUS PUBLICATIONS
Referencias:
Año: 2010 vol. 10 p. 1661 - 1669
ISSN:
1680-7316
Resumen:
In these experiments, the electric charge carried by single particles ejected from the surface of a graupel particle growing by riming was measured. Simulated graupel pellets were grown by accretion of supercooled water drops, at temperatures ranging from $-2$ to $-10 \unit{\degree C}$ in a wind tunnel at air velocities between $5$ and $10\ m\ s^{-1}$, with the goal of studying the charging of graupel pellets under conditions of secondary ice crystal production (Hallett-Mossop mechanism). The graupel, and induction rings upstream and downstream of the graupel, were connected to electrometers and analyzing circuits of sufficient sensitivity and speed to measure, correlate and display individual charging events. The results suggest that fewer than $1\%$ of the ejected particles carry a measurable electric charge ($> 2fC$). Further, it was observed that the graupel pellets acquire a positive charge and the average charge of a single splinter ejected is $-14\ fC$. This mechanism of ejection of charged particles seems adequate to account for a positive charge of around 1pC that individual precipitation particles of $mm$-size could acquire in the lower part of the cloud, which in turn could contribute to the lower positive charge region of thunderstorms.