Clouds - properly known as Stratocumulus or Altocumulus
Lenticularis, depending on height. I have only seen these
very occasionally in the Welsh skies. These
weird, stacked lens-shaped clouds can form when strong
winds flow over mountainous terrain. Hence, they are
orographic clouds, dependant in their formation on the
kind of terrain the wind is blowing over. In Wales they
are most often seen when strong easterlies are blowing.
The strong air-flow creates a distinct up and down
wavelike pattern in the air on the lee side of a mountain
and the lenticular clouds tend to develop at the peaks of
these waves. They
vary from very to extremely photogenic!
This example was seen over Snowdonia in July, 1997. An area of high pressure was sat over Scotland, with a thundery low in SW England. Conditions were very hot and breezy - and a bit hazy.
December 2002, view northwards from Friog over Barmouth. An easterly wind was producing occasional lenticulars in the lee of the mountains - in this case the Rhinogau.
October 1990, Glen Lyon to Loch Tay, Scottish Highlands. An afternoon off work and a new fall of snow on the tops prompted an explore, so I drove up Glen Lyon, thinking to cross over the Ben Lawers range and down to Loch Tay. Here is some beautiful cirrus, plus overhead jet-trails, looking northwards across Glen Lyon from the pass.
There was snow on the road but I had a landrover to play with so no worries....
Looking down the pass with single and stacked lenticular clouds visible on the other side of the Ben Lawers range.
This was the scene that greeted me as I reached the Ben Lawers car-park! It's as though the thing is bearing down, to collide with the mountain and obliterate it. But it just hung about where it was....
I stayed at the car-park for ages and then towards sunset I set off down the steep lane to join the Killin-Aberfeldy road that runs along the northwestern shore of Loch Tay. The clouds persisted so that I was able to stop and get this pic, before darkness fell.
All in all an interesting afternoon's weather photography, 10 years before I started taking the subject seriously!!
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