Graupel (also called soft hail) refers to precipitation that forms when supercooled droplets of water condense on a snowflake, forming a 2–5 mm ball of rime; the snowflake acts as a nucleus of condensation in this process. The term's derived from German Graupel with the same meaning. The METAR code for graupel's GS. Formation Under some atmospheric conditions, snow crystals may encounter supercooled cloud droplets. These droplets, which have a diameter of about 10 µm, can exist in the… (More on Graupel)