Collision-Coalescence process of precipi- tation is applicable to

The collision-coalescence process is the primary mechanism for precipitation in 'warm clouds,' which are defined as clouds where the temperature remains above 0°C (the freezing level) throughout. In these clouds, precipitation forms as larger water droplets fall faster than smaller ones, colliding and merging (coalescing) with them to grow into raindrops. This process is distinct from the Bergeron process, which occurs in 'cold clouds' that extend above the freezing level and involve ice crystals. While collision-coalescence can occur in the lower, warmer parts of deep clouds like cumulonimbus, it is the exclusive mechanism for clouds that do not reach the freezing level. Therefore, the process is fundamentally applicable to clouds that do not extend beyond the freezing level, where ice-phase processes are absent.