I've watched the snow would disappear at this time of year for years. The past two years I've had lots of time sitting in front of the window to just watch. At the moment it's disappearing steadily as we have day after day that creeps up above the freezing line.
We all say the snow is 'melting', but in fact I hardly ever see it melting on the surface. If there's a creek or ditch nearby you might see the snow melt along the edge and run away in a trickle, but I don't see this when I look out the window. I still just see a sheet of white, although it's getting thinner and thinner. So I've been trying to educate myself and I start from the fact that 'melting' is the change from a solid state (snow) to a liquid state (water).
In fact much of the snow doesn't disappear this way, it vanishes directly into the atmosphere, changing from a solid state (snow) to a gaseous state (water vapour) without ever becoming liquid. You can't see this happening, but you can see that the snow is disappearing steadily, and sometimes fast depending on the sunshine and temperatures. The snowpack gets thinner and thinner; green patches of grass appear, and the sidewalks are bare. This, I've learned is actually the process of 'sublimation' a word that we don't use often, but we should use instead of saying that the snow is 'melting'.
The snow is certainly sublimating around here these days. The resulting water vapour has even led to foggy mornings and cancelled school buses.
As I explore the process further though, I learn that the snow actually is melting at the same time. It's melting at the level of individual snow crystals, and the water is trickling down through the snowpack to recharge the groundwater. Maybe you could see this if you got out on your hands and knees with a magnifying glass, but I certainly don't see it.
As both these processes happen the entire structure of the snowpack changes. Snow crystals may start out as light and fluffy, but as they melt or partially melt they recrystallize in the lower temperatures overnight and end up smaller, icier and more densely packed. Squirrels walk across the surface of this snowpack instead of disappearing in the white fluff. I've experienced a time or two when I could walk across the surface of the snow without breaking through, abandoned my snowshoes, and just walked on foot.
So when we talk of snow 'melting', it's actually disappearing in both directions, 'melting' downwards into the ground, and 'sublimating' upwards into the atmosphere. You don't actually see much of either process happening, but my impression is that more disappears into the atmosphere than melts into the groundwater.
What we need is a new word to express both of these processes happening at the same time. Any suggestions?