What are tiny dust or salt particles that help condensation of water vapour called?

Correct answer: Condensation nuclei

Correct answer: C, condensation nuclei. Water vapour does not usually form cloud droplets entirely in empty air. It condenses more easily on very small airborne particles, including suitable dust, salt, smoke, or other aerosols. These tiny surfaces are called condensation nuclei. They provide a place on which water molecules can gather and form microscopic droplets; cooling and sufficient moisture are still necessary for cloud formation. Option A, rain shadow, is a relatively dry area on the leeward side of a mountain and is not a particle. Option B, wind slope, is not the name of a condensation particle. Option C is correct because nuclei are the starting surfaces for droplet formation. Option D is wrong because a dry zone is a climatic or geographic area, not a microscopic atmospheric particle. Memory cue: a nucleus is a centre or starting point; a condensation nucleus is the tiny centre around which a droplet forms.