Thursday, May 03, 2012

Radiatus clouds over the Fens

click photo to enlarge
As a paid up member of The Cloud Appreciation Society and the proud owner of "The Cloudspotter's Guide" you'd think that I'd have no difficulty in naming the type of cloud shown in today's photograph. But I do. I had no trouble identifying it as something relatively unusual in my part of the world, and perhaps a suitable subject for a photograph, or a background to a shot. And I had no hesitation in making the effort to find some foreground interest in a quite open and flat area of the Fens. But as for a name for this cloud formation, well, that required a bit of research that I still haven't completed.

From earlier reading I did remember that some of the basic clouds have what is described as a "radiatus" form. That is to say, they form lines more or less parallel with the wind direction and the perspective effect makes them seem to converge towards the horizon. I've seen cumulus clouds do this, and very striking they were too. I've also seen it in high-level cirrus clouds. The clouds in the photograph, however, weren't the former that are fluffy cotton-wool balls, nor did they seem particularly high and white as is characteristic of cirrus. They don't look like stratocumulus, and probably they aren't altocumulus either. Are they altostratus? They certainly have a greyness about them that is prevalent in that form of cloud. I just don't know. Perhaps someone can enlighten me.

When I searched for a composition for my photograph it occurred to me that I should try and include an element that worked with the lines of cloud, so I positioned myself next to a section of road that curved round towards the "vanishing point" and waited for a container lorry to pass by. Fortunately this quite colourful one quickly appeared on the scene.

photograph and text (c) T. Boughen

Camera: Canon
Mode: Aperture Priority
Focal Length: 24mm
F No: f7.1
Shutter Speed: 1/320
ISO: 100
Exposure Compensation:  -0.33 EV
Image Stabilisation: On