a rare natural phenomenon in which a hairy, woolly ice structure formed of dead and wet heartwood,not on the bark of deciduous trees.
Frost flower can occur even if the air temperature is below freezing. In the timber mold coming before and in the metabolism of these molds is partly free water which through very small openings in the wood (wood beams) is forced outwards. The pressed out water freezes to a hair-like structure.
Haarijs is also known as "the beard of King Winter.