I looked them up in the kids weather encyclopaedia and sure enough Lenticular Clouds, a quite rare occurrence in Britain, needing specific atmospheric conditions more usually found at high altitude mountain ranges.
|Lenticular Clouds high over the East of the Derwent Valley|
|Quite a spectacle|
It's all a bit technical for me but here's a layman's explanation hacked together from the internet :
Lenticular clouds, technically known as altocumulus standing lenticularis, are stationary lens-shaped clouds that form at high altitudes, normally aligned at right-angles to the wind direction.
Where stable moist air flows over a mountain or a range of mountains, a series of large-scale standing waves may form on the downwind side. If the temperature at the crest of the wave drops to the dew point, moisture in the air may condense to form lenticular clouds
Under certain conditions, long strings of lenticular clouds can form, creating a formation known as a wave cloud. As the moist air moves back down into the trough of the wave, the cloud may evaporate back into vapour. So lenticular can appear and disappear relatively quickly.
Indeed just a few minutes after I took those photographs the formations changed completely so unfortunately the kids didn't get the chance to see them. And here are some examples of how spectacular they can be :
Nature at it's breathtaking best.