I heard a Strange Sound as it happens just a couple of months ago. It was on the North Top of Na Gruagaichean in the Mamores, on 17th February [2003], at about 1pm. The weather was clear, with high pressure, and a stiff breeze of perhaps 20-30mph. We were above the snowline: the snow was firm neve, requiring crampons.

The sound resembled two sharp flaps of a large sheet of polythene. It appeared to come from just down the western flank. Two of us heard it, and were surprised, and couldn't work out what it was. I tried to peer over the edge, but it was slightly corniced and that slope is very steep; if anything had been there I would not have been able to see it.

My hypotheses at the time, starting with the least plausible, were a very small alien spacecraft, a bivvybag attached to a frozen-on dead climber, a large fertiliser bag passing on the breeze, or something else


There seem to be three different sorts of Strange Sound being described. There is Dave Hewitt's Very Small Whirlwind: there is the Flapping Plastic of Charlie Stephen and myself: and there is the original fast-moving swish. I think I can explain the fast-moving swish as a process called 'Firnification'. 'Firn' is the German word for the French 'Névé', meaning firm snow suitable for crampons. It is part of the process of recrystallisation by which freshly fallen snow is transformed into, eventually, glacier ice. On hot afternoons with the snowpack at around freezing/melting point, the recrystallisation can take place quite suddenly, stimulated by a passing foootfall. There is nothing to see, but the sound is a mystifying swish. it's like an invisible horseman galloping rapidly away in all directions on skis.

Ronald Turnbull