Ice accretion from freezing rain.
"Ice accretion" occurs when rain falls from an elevated above-freezing air layer into a colder, sub-freezing, air layer near the ground. This causes the liquid rain (or drizzle) to freeze on contact with surfaces whose temperature is at or below 0°C. Prolonged or heavy freezing rain events can result in a coating of clear ice several centimetres thick on vegetation, building structures, vehicles and transmission lines and towers.

Reproduced by permission of Ben Hansen. From Ben Hansen, Newfoundland Gems (St. John's, Newfoundland: Vinland Press, ©1996).