Bb. Demoz et al., AN ANALYSIS OF SIERRA-NEVADA WINTER OROGRAPHIC STORMS - GROUND-BASED ICE-CRYSTAL OBSERVATIONS, Journal of applied meteorology, 32(12), 1993, pp. 1826-1836
Systematic observations of the sizes, shapes, and degrees of riming of
ice particles falling at a downwind station of a major mountain barri
er are presented. The observational station was equipped to measure ic
e-particle masses from 1 mu g to a few milligrams, and to measure ice-
particle dimensions, habits, degrees of riming, and degrees of aggrega
tion. The results are shown to be useful in learning where ice nucleat
ion and growth take place in the cloud system. The present study analy
zed dissipating and developing winter orographic storm systems, which
are representative of more than 60% of the storms observed over the st
udy region. It suggests that most of the needles and columns observed
at the ground may be formed by secondary ice production. Heavy riming
was associated with light precipitation, while high precipitation rate
s were correlated with a high number fraction of aggregate crystals. A
ggregation was found to be important in the process of precipitation d
evelopment and the aggregate mass was mostly contained in the dendriti
c crystal growth region.