Frost flower

Haareis, sometimes also called Eiswolle, consists of fine needles of ice that can form on rotten and damp dead wood in appropriate conditions. Unlike hydrometeors (eg Raureifkristalle ) Haareis arises out of the water contained in the wood, not from humidity.

Look-alike and often not distinct groups of phenomena are Bandeis (german ice ribbons, ice flowers ) to plant stems and Kammeis (English needle ice ) on the ground, but both are formed differently.

Formation

Scientifically the emergence of the rarely observed hair ice is still poorly understood. Described in 1918 the meteorologist Alfred Wegener Haareis on wet dead wood. He suspected a " moldy mushroom" as a trigger, but this was disputed by other scientists accepted the purely physical processes such as in the development of Kammeis as the cause.

A biophysical study of Gerhart Wagner and Christian Mätzler Wegener's assumption was confirmed in 2008 largely. Thus Haareis is the mycelium winter active fungi (among Hose and Stand mushrooms ) triggered their aerobic metabolism ( catabolism ) produces gases that displace the existing wood in slightly supercooled water to the surface. There it freezes and is pushed further by nachdrängende, also freezing when exiting the timber liquid. This happens only at temperatures just below freezing if the water is not frozen in the wood, it freezes at the slightly colder ambient air, however. A boundary condition for the Haareisbildung is also Humidity: If the air is not saturated with water vapor, the fine ice crystals sublimate shortly after their formation at the wood surface, so no long Haareiskristalle may arise. A reproduction of Haareis is as long as possible in experiments, such as the fungal mycelium is not killed in the wood body.