On 29 Aug, 12:44, "JamesB" wrote:
Hey all.
A few weeks back I caught sight of a very odd looking cloud out of my
window. Has a bit of a nuclear mushroom cloud thing about it! Can anyone
explain how it formed?

http://www.puffle.co.uk/weather.php and it's the last one in "other
clouds". Sorry it's not a great pic, only had my phone handy!

James.

I think you are seeing the horizontal extent of this cloud as vertical
extent.