Subzero winter temperatures can produce quite stunning lighting effects.
As one example, since Tuesday night residents of Lahti have been busy sharing photos of vertical columns of light emanating from street lights all across the city.
"The phenomenon is reminiscent of the searchlights, which were used to spot planes in the sky during the war," is how Hannu Valta, a meteorologist at the Finnish Meteorological Institute (FMI), describes them.
Valta added that a similar light phenomenon can be seen during winter frosts at sunset.
These pillars of light are created when moisture in the air turns directly into ice crystals. According to Valta, the crystals are hexagonal and pillar-like. They can reflect the light of a street lamp as they descend very slowly towards the ground.
"Seen against the horizon, it looks like a searchlight pointing upwards," he explains.
The phenomenon requires temperatures of -20 degrees Celsius or colder. The sight is more often seen in the northern parts of the country than in southern Finland, where such conditions are less common.