Marko Posavec Photography

Southwesterlies and temperatures well over 10°C, yep, it’s December. With weather situations like these the sky is usually dull, either featureless with mid-altitude clouds or generally sunny with high-altitude clouds. The latter was to blame for the psychedelic skies – in other words, the brightest display of iridescent clouds I have seen to date.

What are these clouds? Look no further than Les Cowley’s remarkable Atmospheric Optics website. Here’s the important part:

When parts of clouds are thin and have similar size droplets, diffraction can make them shine with colours like a corona. In fact, the colours are essentially corona fragments. The effect is called cloud iridescence or irisation, terms derived from Iris the Greek personification of the rainbow.

The usually delicate colours can be in almost random patches or bands at cloud edges. They are only organised into coronal rings when the droplet size is uniform right across the cloud. The bands and colours change or come and go as the cloud evolves. They occur most often in altocumulus, cirrocumulus and especially in lenticular clouds. (source).

I wasn’t planning to capture these clouds. In fact, I set out to Lake Šoderica to take some photos of our local windsurfers trying to catch some wind on the chilly waters.

But my attention was soon drawn to the sky, especially to the clouds near the Sun. This is an iridescent cloud, a rather nice one.

Not bad, not bad… By now I was already pleased with the sight, but there was more on the way.

OK, now we’re talking! This one was so bright that the colors were invisible to the eye because of sheer luminosity. Underexposing made them appear. And I actually desaturated them in post-production because I thought no one would believe the original image.

Good timing, my black winged friends.

A wider shot reveals where they were in relation to the Sun.

Elsewhere, the sky was… typical.

Then the iridescent cloud began to dissipate and the colors attained subtler hues. Damn, that was good.

Look at this beauty.

The final shot before the cloud faded away. Also, my favorite one.

And check this out. One of those colorful clouds was so bright that its vivid colors could have actually been seen reflected on the water! How cool is that?

Then the show ended, what follows are more earthly pics. Here’s a greylag goose, Anser anser.

It was standing on one leg. They do this to regulate their body temperature.

Now it’s meeting a mute swan, Cygnus olor.

This is one of the prettiest spots on the lake. It’s accessible again, after the recent high waters receded a little.

Painterly skies and dark waters.

As the Sun slowly approached the horizon, the wind picked up – fortunate for the windsurfers.

They sure enjoyed it.

Then the Sun went down and Orion came up. The constellation of Gemini is to the left; some Geminids flew over as well. There’s a fire burning in the field, I wonder what was that about.

Moral of the story: even when the sky looks dull, interesting stuff can be found up there.