In which process do small droplets collide and join to form larger drops?

Correct answer: Collision and coalescence

Correct answer: A, collision and coalescence. Inside a cloud, many tiny water droplets move with air currents. When droplets collide, they may join together; this joining is called coalescence. Repeated collisions make some drops larger and heavier. When a drop becomes heavy enough to overcome the upward air movement, it falls as precipitation, often rain. Option A names the actual microphysical process. B refers to geological events and does not describe cloud droplets. C concerns salt concentration and ocean tides, not the growth of raindrops. D describes the breakdown and removal of rocks, so it is also unrelated. Memory cue: collision means “hit,” while coalescence means “join.” Both steps together help tiny cloud droplets become larger raindrops.