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<br />1880
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<br />-20.0
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<br />JOURNAL OF CLIMATE AND APPLIED METEOROLOGY
<br />
<br />VOLUME 22
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<br />FREQUENCY IN CL OUD (%)
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<br />FIG. 4. Percentage of flight in cloud by temperature for area-wide,
<br />banded and cellular echo combinations.
<br />
<br />The distributions of L WC, ICC, and the ratio of
<br />L WC/ICC are shown for the area-wide echo types in
<br />Figs. 5a-c, respectively. The LWC rarely exceeded 0.2
<br />g m-3. ICC in area-wide echo types was characterized
<br />by a narrow distribution of concentration from 10 to
<br />100 L -1 and by little temperature variation. LWC/ICC
<br />ratios were found to be as large as 100 JLg per crystal
<br />near the freezing level with a decline of ratios (to 10
<br />JLg per crystal) at lower temperatures. Ice crystals dom-
<br />inated liquid water, especially at temperatures less
<br />than -50e.
<br />The banded conditions, display~d in an analogous
<br />manner in Figs. 6a-c, are similar to those found in
<br />the area-wide episodes. Relatively less LWC was ob-
<br />served near the freezing level, though more L WC was
<br />found at temperatures less than -50C. Liquid water
<br />contents> 0.25 g m-3 were found at temperatures
<br />from -5 to ~150e. Ice crystal concentrations were
<br />more broadly distributed than were those observed in
<br />the more stable echo types. Large concentrations, 100
<br />to 1000 L -1, were dominant at temperatures less than
<br />-50C, whereas lower values, down to 1 L -1, were found
<br />at greater temperatures. L WC/ICC ratios show virtually
<br />no difference from ratios observed in the area-wide
<br />echo environment.
<br />Results for the cellular echo types are shown in Figs.
<br />7a-c. Water contents were greater than those in the
<br />other two echoes discussed, with LWC above 0.5 g
<br />m-3 observed. The distribution oncc was very broad
<br />with occurrences observed from 0.1 to nearly 1000
<br />L -I. Of perhaps most significance is the measurement
<br />of low ICC, a phenomenon virtually absent in the
<br />area-wide and banded echo types. The L WC/ICC ratios
<br />are more widely distributed with ratios above 100 JLg
<br />per crystal frequently observed.
<br />
<br />c. Distribution of L WC and ICC in vertical cross sec-
<br />tion
<br />
<br />To formulate useful generalizations regarding the
<br />relationship between microphysical parameters and the
<br />terrain over which they are measured, relative fre-
<br />quency distributions of LWC, ICC, and LWC/ICC are
<br />presented in an east-west vertical plane roughly per-
<br />pendicular to the Sierra crest. In orographically en-
<br />hanced storm environments, specific orographic fea-
<br />tures can be distinguished by an increase of L we.
<br />Some of these L WC maxima on the windward side of
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<br />FIG. 5. (a) LWC distribution shown as a percentage of in cloud
<br />observations by 2.50C temperature intervals for area-wide echo types;
<br />(b) same as (a) except ICC shown; (c) same as (a) except LWC/ICC
<br />shown.
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