The recent cold snap in the US produced some unusual weather phenomena, including waves of icy slush. Nicknamed “slurpee waves” after an American ice-slush fizzy drink, the waves were spotted in a bay in Nantucket, Massachusetts, early in January.
The temperature had fallen to -11C (12.2F), well below the freezing point of sea water. Small particles of sea ice, known as frazil ice, had started to form, but the action of the waves prevented them from aggregating into sheets. This slush is more viscous than water, so the waves move in slow motion and are eerily quiet, the usual sound of crashing surf being completely muffled.
Although this condition is rare, it was photographed in Nantucket before, during 2015. It is no coincidence that this is a surfing beach. The large waves keep the ocean from freezing over, and the popularity of the site means that there were surfers present, even in January, to witness the effect, when other beaches were deserted.
This kind of crushed ice effect can only occur when there is a fine balance between temperature and movement. The slushy waves lasted a few hours before the sea froze over completely and all was still.
