Category: "Pavement ice-water patterns"

Strange dry shadows

February 14th, 2019

Sunshine on pavement seems straightforward enough. It warms the surface, driving evaporation (or sublimation), and dries things out. Conversely, we know that moisture tends to collect on surfaces that are either colder or closer to a water source. And the moisture tends to persist more if the region is more enclosed. Agreed? Now, does anything look strange about these shadows?

Strange dry shadows

The shadows of these snow clumps appear to be dry pavement, the regions in the sun moist. As the sun moved across the sky, the shadows moved, and once dry pavement that was formerly in the shadow became moist as it came into the sun. The image below was taken three hours later.

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