Melting

Warm temperatures are starting the meltdown process again after last week's brief delay. This is not the sharpest picture, but I hope you can see the interesting melting pattern outside my window. You are looking at the snow on my deck with the tips of trees showing above (and behind) it. The light spots below the top of the snow are actually gaps. What is causing this?

The topmost layer is dense ice created by melting snow that drips off the roof and then refreezes into a solid layer. Underneath this dense ice is snow deposited during the last snowfall or blown in by the wind. When the afternoon sun hits this side of the deck, it melts the porous snow much faster than the ice, and these fanciful gaps result.