Here in Fairbanks, the winter weather conditions are often just right for a phenomenon my uncle refers to as “lazy snow.”
When one snowflake lands on another, some of the kinetic energy involved in the collision is converted to heat. If it is warm enough outside, that tiny amount of heat is sufficient to melt a portion of the contact area. If it is cold enough outside, the melted bit refreezes and the two snowflakes are spot-welded together. Technically, this is called sintering.
Piles of snow will deform under the force of gravity. So, a line of snow that forms along a narrow horizontal surface, such as the light pole over my garage, can sometimes sag to one side and slowly pull loose. The sintering of the snowflakes leads to connections that are strong enough for snow to form garlands that can hang a considerable distance below the surface they formed on. As more snow falls, the garlands can be reinforced by the addition of more snowflake bonds.
Last winter, a garland formed on the arm of one of the traffic lights in town. It was well over a road lane in length, hung about three feet below the arm at its lowest point, and was at least a foot thick. It lasted long enough that people heard about it, came to see it, and were trying to miss the green light in order to take pictures. Our entertainment options are limited in the winter season.
