Industrial snow occurs near sources of heat, moisture and atmospheric particulate matter. It usually occurs at nighttime, in a combination of freezing temperatures, stagnant low stratus cloud or fog, and a temperature inversion. [1] It falls from a low altitude as fine spikes of ice, having not had time to grow to the more usual shaped snowflake. [2]
It has been observed in Switzerland, Austria, [1] [3] Germany, [2] Northern Italy (where it is referred to as neve chimica, "chemical snow"), [4] Hungary, [5] in Canada (where it was referred to as refinery snow, or plant snow), [6] the United Kingdom, [7] and Texas. [8]