Observations on the nature of clouds and their glaciation

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Clouds have a significant effect on atmospheric processes such as formation of precipitation and radiative energy transfer. The precipitation efficiency and optical properties of clouds are related closely to nature and state of clouds.Knowledge on nature of clouds and their glaciation is indispensable for elucidation of the effects of clouds on atmospheric processes. Therefore, observations on nature of clouds and their glaciation were made in this study. This report presents the three results of a study on nature of clouds and their glaciation.(1) Development of video measuring probe of cloud particles In order to measure species, size and concentration of cloud particles directly, a handy video measuring probe of cloud particles was developed. Cloud particles collected on slide glass by means of impaction method are photographed by a CCD camera after magnification. Cloud particles larger than about three microns in diameter are detected by this probe.(2) Aircraft observation on microstructure of clouds The size distribution of cloud particles and cloud water content for clouds near Nagoya and Amami Island were observed with the cloud droplet spectrometer (PMS in USA, Model FSSP-100) and video measuring probe mounted on an aircraft (Cessna 404). It was suggested from these observations that size of cloud droplets and cloud water content may be modified by glaciation of water clouds.(3) Observations of nature and state of ice clouds Number concentration of ice crystals in wintertime clouds were observed with sedimentation and impaction method at Shiga Heights. Top temperature of clouds over Shiga Heights were inferred from IR images of GMS. It is inferred from the observation that many ice crystals are possibly formed by some ice enhancement in clouds over Japan, if reported data on ice nuclei are correct.