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The Effect of Updraught Velocity on Splinter Production at Constant Temperature

Author:
[ Alireza Sadeghi Hosseini ] - Geophysics Institute, Tehran Unibversity

Abstract:

Ice initiation in clouds, a most important field of meteorological researches during the last 50 years, has been of special interest to cloud modification scientists. However, despite many success in this field, there remain numerous ambiguities in the ice nucleation process. One of the most important source of ice production within clouds is Hallett-Mossop (H-M) ice multiplication process. In this research work, The H-M process was analyzed at a relatively constant rime surface temperature (T, = -5°C) and liquid water content (LWC = 0.93 gm-3) over a high range of updraught velocities than before (from 1.5 to 12 ms-') with a rotating rod apparatus with radii of either 15 or 25cm. Experiment detected a local maximum of about 35 to 40 splinters per mg of rime close to 3 ms-'. In addition, for the first time it was detected that there is a maximum rate of 60 to 70 splinters per mg of rime at updraught velocity of 6 ms-', possibly due to a combination of rime texture change from feathery to kernel and the ice shell - fracture process. It was found that the radial accelleration at constant updraught velocity did not have significant effects on splinter production.

Keywords:

Ice initiation in clouds , Cloud modification , Nucleation processes , Ice multiplication process , Rime , Cloud liquid water content , Cold cloud chamber , Updraught velocity , Ice splinters , Ice shell - fracture process