No abstract

Experiments indicate that secondary ice crystals are produced when rime grows in a supercooled cloud containing drops > 24pm in diameter. This occurs between temperatures of -3 and -8"C, the production rate being greatest at -5°C. These temperatures are constant to about f05deg C for velocities of the riming body ranging from 1.4 to 3.0m s-:. On average, one ice splinter is thrown off for every 250 drops of diameter > 24pm accreted, at cloud temperature -5"C, and this value does not change much with target velocity. Various possible splintering mechanisms are discussed.

No abstract

Secondary ice crystals are thrown off when supercooled cloud drops are captured and freeze on a moving target in a cloud at -5 degrees C. The rate of production of these ice crystals is proportional to the rate of accretion of drops of the diameter >/=24 micrometers.

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.