An investigation of the effect of urban smoke particles on the cold clouds snow crystals precipitation

The smoke particles in the air of the polluted cities can affect the cold precipitation in these areas. In generall most of the clouds are cold clouds in the geographic latitudes where Iran is located. Cold clouds contain ice crystals and the laboratory study of ice crystals formation in the presence of different particles can provide an opportunity to investigate clouds microphysical processes. Therefore, in this study, the formation of ice crystals is examined in a cloud chamber. Results show that depending on temperature and humidity, ice crystals with different shapes and sizes can be formed. The size distribution of ice crystals obtained for the constant temperature of -21°C in the presence of the environmental aerosols and smoke particles, shows that smoke particles reduce the average diameter of the ice crystals that can have a negative effect on the precipitation. Most of the ice crystals were plates and columns. For temperatures around -15°C, it seems that the growth rate has a peak around this temperature and the ice crystals have the largest diameter on average. Such findings can improve our understanding of precipitation of snow in urban areas and can improve cloud microphysical numerical models and climate modification operations.

کلیدواژه ها:

ice crystals ، precipitation ، size distribution ، smoke particles ، replication method