RELATIONSHIPS BETWEEN TROPICAL PRECIPITATION AND KINEMATIC CLOUD MODELS
Progress rept. no. 2, 1 Aug 1962 - 31 Oct 1962
TRAVELERS RESEARCH CENTER INC HARTFORD CT
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A system of conservation equations embodying conversion of cloud to precipitation and cloud collection by precipitation are examined. The steady precipitation rate at the base of a model updraft column is shown to be a maximum when cloud conversion and collection are completeABOVE THE LEVEL OF NONDIVERGENCE AND ZERO BELOW THAT LEVEL. The decrease of saturation vapor density with height, characteristic of the atmosphere, implies that for any cloud-water content, there is a levelcompensation level above which the cloud density decreases with ascending motion, and conversely. For a particular choice of the magnitude of cloud collection, the precipitation rate at the ground and its time of onset is rather insensitive to the rate of cloud conversion. The efficiency of precipitation production at the earths surface by transient disturbances in a saturated model atmosphere decreases with increasing speed of the updraft. Paths for further study of the role of cloud conversion and cloud collection processes for the initiation of precipitation are indicated. The difference between the horizontal speed of raindrops and the horizontal wind speed is almost always less than 1 of representative horizontal winds.