Vol. 16, issue 02, article # 15

Abstract:

Using eight-term observational data for cloud amounts in Saint Petersburg, Belogorka, and Sosnovo, we have analyzed diurnal cloud variations and estimated the role of radiative-thermal and dynamical factors in the cloud formation. We found that the main role in formation of all cloud types is played by dynamical factors, such as synoptic-scale vertical motions, height variations of their velocity, and associated temporal increase of the vertical temperature gradient. The contribution of the radiative-thermal factor does not exceed 30% in most cases.