ICE CRYSTAL OBSERVATIONS AND THE DEGREE OF RIMING IN WINTER PRECIPITATION

Since snow crystals provide information on the processes leading to th eir formation and growth, their observation gives insight to the micro physics of cloud and precipitation. The capture of supercooled cloud d roplets by snow crystals (riming) forms an important link between prec ipitation and cloudwater and thus plays an important role in wet depos ition. In the project 'Winter Precipitation at Mount Rigi' ice crystal s are collected at two stations at different elevations. The shape, si ze and degree of riming of each crystal are analyzed for more than 100 00 crystals. Differences in the degree of riming of the crystals betwe en the higher and the lower station are discussed. With the aid of Dop pler radar data the location of snow crystal origin is estimated. Furt hermore a relationship between the degree of riming of snow crystals a nd the vertical Doppler velocities is established.