Graupel(redirected from Groupel)
Also found in: Dictionary.
(also soft hail), a solid type of atmospheric precipitation in the form of opaque, white, frosted spherical pellets with a diameter of 2–5 mm. Graupel particles, in contrast to snowflakes, do not have a discernible crystalline form. They are created by coagulation processes (seeCOAGULATION OF CLOUD ELEMENTS) as snow crystals pass through clouds containing supercooled drops of water. Upon collision, the drops settle on the crystals and form snowlike pellets. Graupel generally falls when the air temperature is approximately 0°C.