Hoarfrost, Down Ampney Village, Gloucestershire.
refers to white ice crystals, deposited on the ground or loosely
attached to exposed objects such as grass, glass or leaves.
form on cold, clear nights when conditions are such that heat radiates
out to the open sky faster than it can be replaced from nearby sources
such as wind or warm objects.
name hoar comes from an Old English adjective that means “showing signs
of old age”; in this context it refers to the frost that makes trees and
bushes look like white hair.
Photo by Nigel Musgrove.