Snow melt patterns

Even though it hasn't snowed significantly in quite a while, it has been so cold that until yesterday virtually every snow flake that fell is still on the ground. The weather has finally (!) warmed up and the snow is starting to melt a bit. I spent some time this weekend wandering around, and was interested to see the snow melt patterns. These are important ecologically.

The photo above shows the pattern around a nice white oak. This tree is on the upper south slope and so gets good sunlight on the south-facing side. Note how the snow has melted around the south side of the tree while the north side still has snow. This is a nice example of the way the savanna oaks influence the microclimate of the understory plants.

I assume that what happens is that the dark tree trunk absorbs heat from the sun and then releases it again as radiant heat, some of which melts the snow.