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Study Analyzes Influence of Atmosphere Near-Surface Layer Properties on Development of Cloud Convection

The formation of clouds and precipitation is affected by the rise of moist air, its cooling, and condensation of the water vapor. The upward motion of air is triggered by either free air convection due to thermal instabilities of the atmosphere, or by the effect of the dynamic factors associated with the passage of atmospheric fronts, or flows around complex terrain.

A number of studies have examined the development mechanisms of free thermal convection depending on the characteristics of the near-surface atmospheric layer including air temperature, moisture, and their vertical profiles.

Dr. Ali Abshaev, a third cycle awardee of the UAE Research Program for Rain Enhancement Science (UAEREP) and Head of the Weather Modification Laboratory at the High Mountain Geophysical Institute of Russian Hydrometeorological Service carried out a study involving a theoretical analysis of the influence of near-surface atmospheric parameters on the development of sub-cloud and cloud convection.

The study proposes a two-dimensional mathematical model of moist air convection in the sub-cloud and cloud layers. The advantage of this model is that it deals with not only the absolute value of the near-surface layer moisture, but also with the crucial role of the water vapor mass fraction gradient.

The study suggests that the development of cloud convection depends on the absolute values of the dew point deficit in a near-surface layer and, in a greater degree, on vertical gradients of water vapor mass fraction. The study also reports ‘explosive convective growth’ at certain critical values of a vertical gradient of water vapor mass fraction.

The results of the study also revealed the possibility of successful stimulation of artificial convection under specific favorable atmospheric conditions. 

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