Diamond dusts are near ground level ice clouds. It is a meteorological phenomenon where microscopic ice crystals form in midair without the need for a seed. This phenomenon can only happen at temperatures at or below water's dynamic arrest point of -39°C, much lower than its freezing point of 0°C. Being able to stay in liquid form below freezing point is known as supercooling. Diamond dusts commonly exist in Antarctica. Ice clouds in general can cause various types of Halos to happen.