The first snow we had of the season had really big snowflakes and I neglected to take photos of them. This most recent storm slowed me down and I took photos. The flakes were much smaller but the air was colder so they lasted longer. Still snowflakes have a very short life span and begin their destruction almost the minute they form. I learned that they can go through three stages of metamorphism. The first one is “destructive metamorphism” when the flake begins to melt ever so slightly and form rounded grains that eventually all become the same size in a snow pack. The space between each one become smaller and the density of the pack increases. I can see that happening as the snow on my deck begins to sink lower and lower. What was once 24 inches is now 17, after one day.
The second phase is “constructive metamorphism”. The snow closest to the ground begins to melt because the ground is warmer than the snow. As it melts the vapor moves up and comes in contact with the cold snow and freezes again, this time in the form of ice crystals known as “depth hoar”. As this happens more free space is made under the snow pack and small mammals can move about under the snow. So from the critter point of view as they walk on the ground their ceiling is made up of tiny ice crystals and what we see from above is snow on the ground. This is great for them on a small scale but on a big scale it causes avalanches because the snow is just sort of floating above the ground and is very unstable.
The third stage is “melt metamorphism” and I can hear that happening as the water begins to drip off my roof.
Have you ever wondered why there is no snow next to trees or the snow looks like it is receding away from trees? I never did but when I read about it, I was like, “go figure, who knew”.
Have a jolly holiday.
Vist more blogs featuring water at Watery Wednesday.