Hail Growth
qAs air rises in a developing thunderstorm updraft, supercooled
cloud droplets are
found between altitudes where the temperature ranges from 0°C to -15°C.
qThe ice particles that form
at higher altitudes can fall back to this supercooled cloud water region and collect the water
to form graupel particles, which are soft ice particle with diameters of one to a few
millimeters.
qThese graupel particles centering around the updrafts form an
embryo curtain (the
blue region) will eventually grow into hailstones.