Observation and Analysis of the Aggregation Growth Among Ice-snow Crystals

The process of the ice-snow crystal running together plays an important part in origination of precipitation. It is a focus in cloud physics research. It discusses the cloud and fog that happens in lab and field observations. Result shows that as the droplets coalesce and grow, there is a speed up process also in ice crystals growth, such as snowflake, snow-circular, graupel and hail that coalesce super-cooled droplets and aggregate among ice-snow crystals. Experiments show, in the lab the shapes are fixed basically in temperature of -3.5- -20 ℃. The aggregate among ice-snow crystals only happens in saturated or super-saturated water level vapor pressure in the lab. While in insaturation (no liquid droplets) it does not happen. In 1 m³ chamber their shapes are dendritic and stellar, and their aggregated mechanism is caught by branches appearing in -13- -17.℃ While in 96 m³ chamber the shapes are needle, columnar, dendritic and stellar, the mechanism is adhesion and adhering appearing in -5- -18 ℃. In field observations of natural cloud and fog, the mechanism of the ice-snow crystal running together is adhesion and adhering appearing in -3- -17 ℃, and their shapes are dendritic, stellar, sector, plate, tabular, needle, columnar and columnar bean.The 1 m³ chamber is 1.76 m high and 0.88 m wide, the experiment is made in-3.5- -20 17. The 96 m³ chamber is 14.8 m high, 3.0 m wide, the experiment is made in-5- -18 ℃. The temperature is measure by three Pt resistance thermometers with the difference of 0.1 ℃ to compare with standards one. The sample that burnt for Silver Iodide pyrotechnic is made by deposit method. A great deal ice crystal aggregates into each other appearing in -13- -17 ℃ in 1 m³ chamber when the sample is exposured for 1 minute. But for other temperatures of -3.5- -20 ℃ it does not. While in 96 m³ chamber the aggregation process happens among ice crystals. Their sizes are lager than 1 m³, because the ice crystals could be maintained for a few hours, and there exists torrent and the ice crystal could move with air in 96 m³ chamber. In field observation, the measurement is made by PMS, 2D-C, 2D-P on aircraft in cloud, and by electronic microscope and the samples making for deposit on ground. The shapes of snowflake aggregation vary in cloud in nature because they could exist long in cloud and exhibit convective and torrent features. The ice crystal could interact with them. Another field observation is made by artificial dispersing fog by liquid nitrogen, and samples are measured by electronic microscope for deposit on ground. The ice-snow crystals running into snowflakes by the mechanism of adhering in -3— -8 ℃, and their shapes are hollow columnar, columnar and needle.