grow much more vigorously to the sizes suitable for helping water droplets to form and make clouds. (A nanometre is a millionth of a millimetre.) ...

When enough water droplets form and cluster together, a puffy cloud forms. But how do the water droplets get there?

tiny airborne particles known as cloud condensation nuclei are required for water vapor to condense and form cloud droplets. But what are the origins of these cloud condensation nuclei?