In order for both water droplets and ice crystals to form, particles called condensation nuclei and ice nuclei need to be present. These could be any fine substance - dust, salt, etc.

Water vapor condenses on tiny particles called cloud condensation nuclei (CCN). Raindrops are about 2 millimeters in diameter, a cloud drop is about 20 microns (.02 mm), and the nuclei is about .2 ...

To explain cloud seeding, first you need to know how clouds form. Clouds form when water vapor and gas rises, cools and ...

All clouds need “seeds” called condensation nuclei or ice nuclei to properly develop. This could be a speck of dust, clay or pollen in the atmosphere. There are several temperature, moisture and air ...

The freezing point of water is anything but a clear subject. Small droplets of the purest water only freeze at minus 37 degrees Celsius. Crystallization nuclei such as bacteria with ice-forming ...

These clouds must contain water that is below freezing, but has not quite frozen yet because the particles necessary (condensation nuclei) for the water to freeze on are not present.

Letter Published: 27 April 1946 Artificial Condensation Nuclei and Relative Humidity NAVINKUMAR DALAL Nature 157, 549 (1946) Cite this article ...

Schematic of the pathways for pore condensation and freezing (Upper Left), deposition nucleation (Lower Left), and homogeneous nucleation of pure water droplets (Right), followed by ice-crystal ...

Clouds are formed when water vapor condenses around microscopic particles in the atmosphere. These particles, called condensation nuclei, are ever-present and come from dust, smoke, salt and even ...

Mercury thermometers are of little use in Arctic winters because they freeze at 37.7° below zero. G.E. researchers kept mercury, free of foreign nuclei, in a liquid state down to an unearthly 109 ...