Secondary ice particle production during rime growth : the effect of drop size distribution and rimer velocity

The rate of production of secondary ice particles during the growth of rime in a supercooled cloud at about -5 "C is known to depend mainly upon the rate of accretion of large drops (diameter 325 pm). New experiments have defined more clearly how 'splinter' production is affected by the rate of accretion of small drops (diameter ~ 1 2 Fm). The relationship between secondary ice production and rimer velocity is explored over a wider velocity range than before. At low velocities, splinter production persists to 0.55 ms' and probably lower. There is no evidence of a low-velocity cut-off as previously claimed. At high velocities, splinter production persists to velocities >5 ms-' . This may have important implications for secondary ice production in hail clouds.