Crescent-Shaped Ice Melt

May 23, 2017


Photographer: Raymond Murphy
Summary Author: Raymond Murphy

The photo above shows a pattern of crescent-shaped melting areas in the ice of the Lachine Canal, in Montreal, Canada. I took the photo on the afternoon of April 2, 2017, from the Saint-Henri neighborhood in Montreal, after the Sun had warmed the area to well above the freezing point. The canal has a slow, steady current from right to left in the picture. Although that’s the same direction the wind was blowing from on this afternoon, I believe the crescentic melting effect is simply water flow induced. Note the regularity of the sizes for most of the crescent shapes.

Crescentic forms in nature, though not common, are sometimes observed; barchan sand dunes for example. More significantly, crescentic erosion patterns have also been observed, such as the crescent-shaped blowout features seen in a few of NASA's photos of Mars (Mars photo PIA13941).

Photo Details: Camera Model: Canon EOS 7D; Lens: EF35mm f/1.4L USM; Focal Length: 35.0mm; Aperture: ƒ/10.0; Exposure Time: 0.0020 s (1/500); ISO equiv: 160.