Hi,
I was actually going to send you and Matt that link this evening Oshyan :-).
This photo is taken just a bit south of where I live. We see clouds like this quite often when the Norwester is blowing. I have quite a lot of photos of them. In fact we had some yesterday evening although they weren't lit up so well.
We haven't had them a lot this year because there haven't been many Norwesters. Normally we get them all through spring and summer. Where I live is on the edge of the mountains running up the middle of the South Island, on the eastern side. The Norwester is a particularly well know wind here, like the Mistral and other named winds :-). What happens is that the wind comes off the ocean on the western side of the South Island and hits the Southern Alps. As it rises the air cools and starts to lose its moisture, which is why the West Coast of the South Island is so wet and has rain forest. By the time it comes over the top of the Alps it is very warm and dry. As it comes down the eastern slopes of the mountains (where we are) it accelerates. We get very strong winds here. Our house had to be engineered to withstand 270 km/h winds! That wind is the Norwester, despised throughout Canterbury :-).
Anyway, this wind creates something called the Northwest Arch, which is like a big upside down U shaped flow of air over the mountains. On the eastern side you often get interesting cloud formations running north/south along the edge of the "arch". These are one of the types of cloud you often see. It's made more dramatic by the fact that sky over the mountains themselves is often cloudless when there's a Northwest Arch.
Funny you should say "if I saw these out the window" :-). My office faces north looking along the edge of the mountains and I often see these clouds.
Regards,
Jo
