Ice and Mixed Phase Clouds - Rimed Crystals

Riming occurs in mixed phase clouds when water droplets are in collision with ice crystals, the majority of riming occurs at temperatures between -5 and -25C. The collision causes the droplet to freeze instantaneously maintaining an almost spherical shape. The figure shows crystals with just a few rime particle attached, where the original crystal shape is clearly distinguishable, and others where there is so much rime that it is impossible to determine the original crystal habit.