In the coldest regions of the world, it happens that some hikers come across amazing ice formations: needles of ice, a phenomenon with a fascinating geometric shape, but also very dangerous.
During a winter walk in the snow, it is better not to stumble and fall on a pile of ice needles. Seen from a distance, this phenomenon may go unnoticed, but when approaching, the needles of ice (also called “candle ice”) resemble icy candlesticks of a few tens of centimeters.
They are perpendicular to the ground, hence the danger they represent. Anyone unlucky enough to fall into it could well end up… transfixed. But very often, the needles are fragile, and the danger is then to believe that one can walk on this thick mass of ice which floats on the water, which breaks in fact at the slightest contact.
There are several types of ice needles, and the most spectacular form on the surface of the water, usually on a polar lake, such as in Canada, Siberia, the Arctic and the Scandinavian countries.
The phenomenon occurs when piles of ice and snow begin to melt and collide with the currents.
Ice crystals, hexagonal in shape, encounter sediments, bacteria or pollutants, which become trapped in the middle of the ice. Melting accelerates around this often mineral material, giving rise to this columnar shape, although the process is not yet fully understood.
Other smaller and less dangerous needles exist under the ground
Another type of ice needles exists on earth, pipkrakes (Swedish term), much smaller: a few millimeters and a few centimeters. These small crystals agglomerate under the periglacial soil during a hard freeze on wet ground. This very small phenomenon can be heard (when walked on) more than it is seen, due to the crackles it emits.