Question

What are condensation nuclei?

Answer 1

Also called cloud condensation nuclei. Tiny particles upon whose surfaces condensation of water vapor begins in the atmosphere. Small nuclei less than 0.2 mm in radius are called Aitken nuclei; those with radii between 0.2 and 1 mm are large nuclei, while giant nuclei have radii larger than 1 mm.

Answer 2

Cloud condensation nuclei or CCNs are small particles typically 0.2 µm, or 1/100 the size of a cloud droplet on which water vapor condenses. Water requires a non-gaseous surface to make the transition from a vapour to a liquid; this process is called condensation.

MAYBE I THINK ;)