can the snow pattern in these pavers be explained?

[misterroy]

Here is the picture:

It shows a friends paved area where the sun has melted the snow over the pavers, but has left a reasonable depth of snow on the joints. Where the sun did not shine the snow is intact.

Has the sunshine got through the snow and heated the pavers, and the melted the snow?

[Tim Lamb]

In message [e-mail], misterroy [e-mail] writes

More stored energy in the paver than the fill material?

[Tim+]

Stored heat in the pavers from the previous day? Different thermal properties of the cement and the pavers might be enough to explain it.

Tim

[misterroy]

It has been cold and snowy for about 4 days, just -2 or so, but I would have thought cold enough, to drain the heat from the blocks and the joints.

[Cursitor Doom]

Image was a bit of a let-down. From the title of your post I was kind of expecting to see the sigil of Beezebub.

[Robin]

But not to "drain the heat" from the sand/MoT/soil below the blocks and joints, leaving the different thermal conductivities of the blocks and joints a *possible* cause of the pattern.

[Jeff Layman]

Snow absorbs infrared almost entirely (transmission <1%) at 800nm and heats up. The photo would therefore suggest that the pavers are a better heat insulator than the joints, as the snow on them would melt earlier than that on the joints, retaining the heat from the IR it had absorbed for longer than that on the joints.

[misterroy]

Thank you Jeff.

[Peter Johnson]

A variation on this: My car, facing south, had been covered in snow that had thawed on the body but on the windscreen, although it had started to slide down towards the bonnet most of it was still there, apparently. I went out last night after dark and found that the surface snow had frozen, leaving a cavity underneath into which I could get my hand, after I had broken a hole in the frozen snow.

[GB]

An alternative explanation :

Water is a better absorber of sunlight than snow. The sand joints allow water to drain through, whereas the pavers don't. So, you get differential melting.