WMOD00310

• Title: Cloud Physics Investigations - University of Wyoming - 1977-1981
• Date: 11/1/1982
• State: WY
• Weather Modification - Doc Type: Report

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spectra result at later times while the initial spectra were unimodal.

The processes responsible for this modification of the droplet

spectra actually produce an increase in the concel1tration of small

droplets in some cases, but the concentration of large droplets was

not observed to increase during the entrainment process.

The observations suggest that the development of broad spectra is

not accomplished in the initial stages of an inhomogeneous mixing

process. While the mixing appears to be highly inhomogeneous, it does

not lead to substantial broadening. Rather, the passage of time appears

to be required for broadening,. and the broadening occurs primarily via

the increase in the number of small droplets. Perhaps the fluctuating

supersaturation fields characteristic of a highly mixed and turbulent

cloud region can lead to sufficient fluctuations in the

time-integrated supersaturation encountered by various droplets to

lead to such a broadening. If cloud droplets in a highly mixed and

turbulent cloud follow varying trajectories in the course of arriving

at a given location, such varying saturation ratios may lead to some

broadening of the spectrum with time.

2.6: Liquid water content. Fig. 2.11 shows the frequency wi th which

the (JW) liquid water content exceeded various thresholds. Measurements

were made each second, and thus were separated by about 100 mi all

values exceeding 0.1 g/m3 were used to calculate relative frequencies.

The truncation at values above 2.5 g/m3 is artificial, as explained

in Cooper et al. (1982a) i this results from the zero offset and

airspeed corrections which we apply, and the inherent 3 g/m3 limit of

our instrument.

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