Black lake ice

Pyhäjärvi lake ice has turned all black. We had lovely walk in Tahmela and Pispala area while Emma had Nikkilä's  center training in Varala.

Once the snow melts off the top of the ice, the ice is exposed to the sun. The ice then acts like a greenhouse to the lake water, and as the sun shines on the ice, it heats the water underneath the ice.  The ice then starts to melt from the bottom, where it is touching the water.  When the ice thickness erodes to between 4 and 12 inches, it transforms into long vertical crystals called "candles." These conduct light well, so the ice starts to look black, because it is not reflecting much sunlight. As the sun continues to heat the ice, the water below the ice continues to warm.  Meltwater fills in between the crystals, which begin breaking apart. The surface appears grayish as the ice reflects a bit more light than before. Then, a windy day to break the surface ice apart.  The ice candles will often be blown to one side of the lake, making a tinkling sound as they knock against one another, and pile up on the shore. 




+10°C, cloudy. -3°C in the morning