HR: 0800h
AN: AE41A-0144    [Abstracts]
TI: Ice Crystals and Corona Discharge: Laboratory Evidence for Ice Multiplication in Thunderstorms
AU: * Petersen, D P
EM: Danyal.Petersen@dri.edu
AF: Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Bailey, M
EM: matt.bailey@dri.edu
AF: Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Hallett, J
EM: john.hallett@dri.edu
AF: Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Beasley, W
EM: whb@ou.edu
AF: School of Meteorology, University of Oklahoma, Norman, OK 73019 United States
AB: The main charging mechanism in thunderstorms is related to interactions between ice crystals and graupel in addition to riming processes, and clouds become electrified only after significant amounts of ice particles are generated. Additionally, ice crystal concentrations are observed to increase with each subsequent discharge in thunderclouds. Recent laboratory experiments addressing corona emissions from ice crystals in strong electric fields have revealed a rapid post-discharge growth mode of ice crystals that might explain these observations. Following corona emission with relative humidity near water saturation, highly charged ice crystals are observed to grow fragile needle-like structures which easily detach from the parent crystal. Observed growth rates of the needles are two to three orders of magnitude faster than normal vapor deposition growth rates, even in the absence of strong external electric fields. The process of growth and detachment can continue for several minutes, potentially resulting in the production of several secondary ice crystals from each parent crystal. The process is likely to inititate in the high relative humidity of the ice - supercooled water interface where sufficient charge separation occurs, but can then continue in other regions with lower field values.
DE: 3324 Lightning
SC: Atmospheric and Space Electricity [AE]
MN: Fall Meeting 2005