Moustache Cloud: The goldilocks of clouds

Tuesday 04th Nov 2014 by theWeather Club

Linda D. Bonskowski snapped this cloud in Martinsburg, West Virginia, but had no idea what she was looking at, so she contacted theWeather Club to find out.

We, like many others, initially thought it may have been a contrail created by some kind of aerial vehicle that had completed a loop-the-loop manoeuvre, but it is difficult to determine from just this static photo without knowing more about the weather conditions at the time. Further research and discussion via social media channels now suggests that it may actually be a very rare ‘moustache cloud’.

Moustache clouds – or ‘horseshoe vortex clouds’ – form in a region of rotating air. These vortices usually form vertically and can lead to funnel clouds, or even tornados. If, however, they develop horizontally, and under the right wind conditions, the updraught may result in a gently rotating crescent of cloud.

As seen in this video, when a cumulus cloud travels over a weak updraught, it may bend and form a rotating moustache cloud (named after its handlebar moustache-like appearance).

According to the Cloud Appreciation Society, “such a movement of air seems to happen when an updraught is sent into a spin upon reaching shearing horizontal winds. Rarely are conditions right for a cloud to appear within the spin.”

One of the best times to spot such a cloud is in the vicinity of a supercell storm, or a thunderstorm with a continuously rotating updraught. However, such clouds appear for just a minute or so before evaporating away, so if this was indeed a moustache cloud, Linda was very lucky to capture it in a photograph!