Frost crystals

Frost crystals are fairly rare phenomenon. They form mostly in still, dry air. The key factor is air that is much colder than the water below the ice, something around -15°C - -20°C. Very cold water droplets in the air will attach to a spot on the surface of ice and freeze. Conditions have be just right. The frost has to form slowly, it takes between hours to days for frost crystals to form. These displays of ice are called frost crystals because they grow by frost being deposited on ice crystals and thus adding to the growing crystals. 

Photographed these at Reippi, I had a short walk on ice in the afternoon with Leevi and Sami. Two more photos as extra. In the morning I had a walk with Saara - time and kilometres fly when having interesting conversations! 


At 8 a.m. -20°C, at 3 p.m. -10°C, at 9 p.m. -18°C.