Black ice (congelation ice) "forms as water freezes on the bottom of the ice cover and the latent heat of crystallization is conducted upwards through the ice and snow to the atmosphere."
Glaciology[edit | edit source]
Black ice "growth rate is proportional to the rate at which energy is transferred from the bottom surface of the ice layer to the air above."
At the right is a vertical thin section through the black ice of the pond. It shows granular snow ice (top) and columnar black ice (bottom).
Water ice[edit | edit source]
"Congelation ice is often referred to as black ice because it has a high optical depth that permits significant light transmission to the underlying water."
The image on the right shows high optical depth and bubbles trapped and frozen under a thick layer of black ice.
Icebergs[edit | edit source]
The first image on the right shows that when the polar sea is calm, the underside of icebergs can easily be observed in the clear waters of the Arctic Ocean.
Centered in the image second down on the right is a black ice growler from a recently calved iceberg closing in on the shore at the old heliport in Upernavik, Greenland. Such black ice growlers originate from glacial rifts, or crevasses, filled with melting water, which freezes into transparent ice without air bubbles.
On the left is an image of the surface texture on a black ice growler. There are bowl-like depressions in the surface created by the melting process of sea water.
Weather[edit | edit source]
"Meteorological factors such as air temperature, precipitation, wind speed and radiation balance coupled with physical characteristics of the lakes and ice (lake area, depth, volume and fetch; snow depth; ice thickness, type and albedo) lead to complex interactions and feedbacks that affect the timing of freeze-up and break-up (ice cover duration) each year."
Earth[edit | edit source]
"Lake ice occurs primarily in the Northern Hemisphere [of Earth], where most of the ice is seasonal: it forms in the autumn, thickens during the winter and melts in the spring."
Locations on Earth[edit | edit source]
In Swedish kärnis means "blue ice", whereas the English term is "black ice". Lots of "blue ice" occurs on lakes with clear water over a sandy bottom. At right is an image of black ice (kärnis) on Lake Vättern. On the left is an image of black ice over a river in Holland.
Hypotheses[edit | edit source]
- Black ice indicates slow freezing.
See also[edit | edit source]
References[edit | edit source]
- ALISON (5 September 2014). LAKE ICE: Ice Formation. Alaska, USA: Alaska Lake Ice and Snow Observatory Network. http://www2.gi.alaska.edu/alison/ALISON_SCIENCE_Lake.html. Retrieved 2014-09-05.