What happens to raindrops when they get too large, approximately 6mm?

Raindrops that grow to a size around 6 mm face the challenge of maintaining their integrity due to the forces acting on them as they fall through the atmosphere. As raindrops increase in size, the drag force exerted by the air becomes significant compared to the force holding the drop together (surface tension). When a drop gets too large, generally approaching 6 mm in diameter, the drag force can overcome the surface tension, causing the drop to break apart into smaller droplets. This phenomenon helps maintain a balance in the atmosphere, preventing excessively large raindrops that could be damaging upon impact.

The other processes—evaporation, accumulation of more water, and freezing—do occur under certain conditions but are not the main events for drops reaching this size. Evaporation typically happens on smaller drops and can be more relevant in warmer air near the ground or in dry conditions. The accumulation of more water primarily happens to smaller droplets as they collide and merge, and freezing is more commonly observed in cold environments, leading to ice crystals rather than large raindrops.