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 ⩾25 mm). New experiments have defined more clearly how ‘splinter’ production is affected by the rate of accretion of small drops (diameter ⩽12mm). 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−1 and probably lower. There is no evidence of a low-velocity cut-off as previously claimed. At high velocities, splinter production persists to velocities >5ms−1. This may have important implications for secondary ice production in hail clouds.