All posts tagged light

Painting by Edvard Munch – Public Domain

Did Edvard Munch paint nacreous clouds? The hypothesis was put forward by Norwegian scientists at the European Geosciences Union General Assembly in Vienna this spring (2017.) The long-held assumption is that the vividly colored sky in The Scream (1893) is a reflection of the artist’s troubled mind. A facile analysis and attractive mostly for the reason that we like to attribute romantic madness to our artists. More careful research is showing that some paintings that have been thought to contain fanciful imagery are really representing unusual meteorological phenomena, such as the lurid sunsets that happened after the volcano Krakatoa (1883) put huge quantities of aerosols into the atmosphere.

Munch himself said in his diary about the incident that inspired The Scream:

I went along the road with two friends – the sun set

I felt like a breath of sadness –

– The sky suddenly became bloodish red

I stopped, leant against the fence, tired to death – watched over the

Flaming clouds as blood and sword

The city – the blue-black fjord and the city

– My friends went away – I stood there shivering from dread – and

I felt this big, infinite scream through nature

Photo credit – Deven Stross

Check out the links and get the rest of the story. Go have a look at the Green Comet Cloud of the Day post on nacreous clouds and see if they look anything like the sky in Munch’s The Scream. This could be speculation, somewhat like my suggestion that Vincent van Gogh might have been inspired by asperatus clouds to paint some of his skies. It is also quite possible that this hypothesis is accurate and that Edvard Munch really did see nacreaous clouds. Personally, I prefer it to the analyses of pop pshycologists.

Photo credit – NASA – PD


Cloud of the Day – International Cloud Atlas

The International Cloud Atlas has recently published a new edition, the first in thirty years. The 2017 edition is only the fifth one, with the first coming out in 1939, so it’s pretty special. The International Cloud Atlas is a product of the World Meteorological Organization, an agency of the United Nations. The Atlas takes much the same approach as I do in their definition of what is a “cloud.” In my Cloud of the Day series I have included many things that aren’t strictly clouds, such as rainbows, haloes and sprites. The Atlas collects them all under the umbrella of meteors. So we have hydrometeors — meteors composed of water — that include things other than clouds, such as fog and rain. And there are photometeors, that are made by light, such as rainbows, etc . Electrometeors include auroras and Saint Elmo’s fire. There are even lithometeors, made of dry particles, like dust and haze. I don’t feel quite so bad now. If the UN can do it, who am I to cavil?

The existing classifications have been reviewed and all have been retained. Several new, formal cloud classifications have been introduced. These include one new species (volutus), five new supplementary features (asperitas, cauda, cavum, fluctus and murus), and one new accessory cloud (flumen). The species floccus has been formally recognized as being able to occur in association with stratocumulus. The separate section on Special Clouds has been removed, and the cloud and meteor types previously discussed within this section have been integrated into the cloud classification scheme as cataractagenitus, flammagenitus, homogenitus, silvagenitus, and homomutatus.

This edition of the International Cloud Atlas includes new additions, including one you might remember seeing here when it hadn’t yet been accepted as a unique type. I wrote about it as asperatus, but they’ve changed the spelling to asperitas. This cloud was championed by the Cloud Appreciation Society, a collection of enthusiastic amateurs, and great photographers.

Photo credit – NASA – PD

Enjoy this fresh edition of the International Cloud Atlas. It has a searchable image gallery.



Levon Biss is a successful commercial photographer. His work has been used in advertising, on magazines and in a book about soccer. Now he has an exhibition of his images of insects, showing the Oxford University Museum of Natural History’s insect collection in stunning detail. The exhibition runs from May 27 to October 30, 2016, and it’s called Microsculpture. The prints range in size up to three meters, each an image of a tiny insect captured down to the finest detail.

These are not just snapshots of pretty bugs. Each image takes about three weeks to complete. He shoots each insect in sections — about thirty on average — and then compiles the shots into a single, complete image. In all, he shoots 8,000 to 10,000 photographs of each bug, then combines the best parts of them into the final product. He needs to get the lighting and the focus just right for each tiny part, so the whole image can be perfectly lighted and focused. Since the depth of field is so small with a microscopic lens, he can only move the camera ten microns between shots. That’s not much more than a tenth of the width of a human hair.

If you want to see the detailed originals of these small samples, follow the links to Levon Biss’s Microsculpture website. There you can see the light reflecting off the individual cells of compound eyes, and count the hairs on little buggy legs. There’s also a video that shows how he did it.

All photos copyright Levon Biss.


Credit Jari Luomaner

Credit Jari Luomaner

Cloud of the Day – Diamond Dust

It is really hard to find good pictures of diamond dust, so I’m going to have to just describe it to you. Diamond dust is a colloquial name given to ice crystals when they are close enough to the ground that they can be seen individually. Ice crystals are also involved in other optical meteorological phenomena, such as halos and sun dogs, but there they are seen in aggregate.

Ice crystals - dave 3457 - Public Domain

Ice crystals – dave 3457 – Public Domain

In diamond dust you are right among them and you can see them separately. Follow the links for the detailed explanation, a picture and a video. As an illustration of being within the phenomenon, the photographer describes how he moved his arm and stirred the thing he was photographing. Now get ready for the mental pictures.

Imagine you are standing in the middle of a snowy field. It’s thirty below, perfectly calm and brilliantly sunny. You have your parka on but it’s partly open and the hood is thrown back. With no wind and the Sun shining, the walk out here has warmed you up. It’s good walking though; the snow has a good crust. Looking at it, you can see that it’s sparkling like mad.

Raising your eyes to the dark trees at the edge of the field, you become aware of glittering and twinkling in the air. Your eyes dart around, trying to catch the colorful flashes of light. You feel combined joy and disappointment, being there for such a magical display, but knowing it can’t be caught and held.

You hold out your arm and within seconds you catch your first flash of light on the dark fabric. Since the surface of your parka has cooled down enough, they don’t melt right away and they are able to accumulate. Soon you have a random scattering of sparkles that shift and change as you move your arm.

Now you look up and you can see that the sky above you is filled with points of light and color, brief flashes that make you hold your breath as you try to take it all in. You see why it’s called diamond dust, because it looks as if tiny diamonds are sifting down out of a clear blue sky. You just want to stand there all day, head thrown back, filling your eyes with this ephemeral beauty, while an occasional bit of glitter gets caught in your eyelashes.

Walking back home, the snow crunching under your boots, you know that this bright, beautiful clarity will become a cherished memory.


An unknown percentage of women can see a hundred times as many colors as the rest of us.  While normal humans have three types of cones in their eyes for perceiving the three primary colors — red, green and blue — some women have an extra cone that gives them four primary colors.  Most of us can theoretically distinguish a million colors.  These women can see a hundred million colors.

Tetrachromatic women have a strong relationship to color-blind men. How does a deficiency — color-blindness — relate to this increased color perception? It has to do with the X chromosome and the fact that the genes for color perception reside on the two sides of it. With only a Y chromosome, and missing one of the arms of the X chromosome, men have less chance for redundancy. If they have a mutation in a color gene it usually means some loss of color perception. Women related to these men will likely have the same mutation, but they will have redundant genes on the second arm of their X chromosome. So the men will be down to two functioning cones, but the women will still have all three, plus the mutated one, which might still provide some color.

More recent research indicates that we might all be tetrachromatic after all. It turns out that parts of our optical system absorb the shortest wavelengths of the light that passes through them. It was assumed that our vision cut off at about 400 nanometers — blue — but it’s been discovered that the higher blues and the ultraviolets are being absorbed by our corneas and lenses. People who have their lenses removed in cataract surgery often report a new sensitivity to very short wavelengths.

Recently the BBC made a tetrachromatic woman famous. Concetta Antico is an artist and she can see colors that most of us can’t even imagine.

Some women are born with hyper-sensitive eyes that can see the world in ways most of us cannot even imagine. What’s it like to live with this gift?

Source: BBC – Future – ‘I see colours you cannot perceive or imagine’

This led to an Internet spasm, of course, and tetrachromacy became all the rage. There were even websites set up that purported to test you for the condition. Soon thousands were reporting on their social networks that they were tetrachromats. Fortunately, Snopes came to the rescue and showed quite simply why they were wrong. Computer monitors only use three colors so they can’t possibly test you for four. The Snopes article refers to Newcastle University’s tetrachromacy research project and credits them in debunking the Internet fad. Newcastle University has a FAQ on their research.

When I look out the window and see all the shades of green and brown in my back lawn, it’s hard to imagine that I’m not seeing it all. Learning that some people can see a hundred times as many shades makes me think about how little of reality I’m really seeing.