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Today in Finland we are enjoying the beauty of blue shadows on white snow – the colours of the Finnish flag as well. With these Outi Kuma’s photographs and Harald Arnkil’s texts about coloured shadows the Finnish Colour Association FCA wishes you all around the world an inspirational International Colour Day 2013 and welcomes you to visit our renewed website, designed by Päivi Hintsanen.
“Mornings and evenings are dramatically different near the Equator compared with the subarctic regions. In latitudes above 60˚N (Alaska, Northern Canada, Greenland, Iceland, Northern Russia and the Nordic countries), in suitable weather one can admire how the rising or setting sun paints the sky with a lingering play of slowly shifting colours. Near the Equator the sun rises and sets abruptly, in only a few minutes. In the evening it seems to drop like a stone and night descends like a velvet curtain, creating darkness quickly and completely – and always at the same time. Sunrise is similar, but in the opposite direction; the penumbra that is typical of the subarctic rhythm of dawn and dusk is almost completely absent.
Everywhere on Earth direct sunlight is always slightly ‘yellowish’. This is due to the Earth’s atmosphere, which scatters short, blue-producing wavelengths of light more than the longer yellow and red-producing ones. At noon near the Equator, sunbeams reach the ground in an almost perpendicular fashion, which gives direct sunlight an almost neutral hue. Closer to the poles, the angle of the light is more oblique, making sunlight pass through a thicker mass of air. There the particles in the atmosphere scatter shortwave radiation from the light more strongly than closer to the Equator, making direct sunlight yellowish.
Despite these physical differences, the total ambient lighting in the far north and south is seldom perceptibly more yellowish in hue than nearer the Tropics and the Equator. The main reason is the way our vision adapts to the environment. – – – A salient feature of northern light is the marked contrast between the hues of direct sunlight and skylight (the light scatted by the sky). For example in midwinter near the Arctic Circle the sun is very near the horizon even at midday; its light has to penetrate a thick mass of air, that colours it to the hue of the rising or setting sun in summer. In contrast to this, due to lack of moisture or pollution, the sky can have a brilliant blue colour that is reflected by the snowy landscape, particularly in the shadows, thus further enhancing the impression of the yellowness of the sunlight. In many latitudes daylight consists of much scattered, often bluish, light from the sky that gives a cool hue to shadows; but it is the contrasting yellowness of the low sunlight of mornings and late afternoons that makes this blueness visible to us.”
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“But from where do colours come into shadows? Firstly, from the indirect radiation of the blue sky, as mentioned above. Shadows turn blue in an objective sense. The sky, of course, also radiates blue into areas with direct sunlight, but this radiation is so weak in comparison with the direct sunlight that it has less relative effect on them. When sunlight becomes yellow due to its low angle, shadows will turn blue also subjectively. Owing to adaptation, we do not often notice the yellowing of sunlight, but its light is very rarely completely neutral. The subjective colouring of the shadows is due to simultaneous contrast. The contrast colour is always the complementary of the stimulus colour. Goethe’s book Zur Farbenlehre (1810) contains one of the earliest descriptions of coloured shadows in the landscape:
In travelling over the Harz in winter, I happened to descend from the Brocken towards evening: the wide slopes extended above and below me, the heath, every insulated tree, and every projecting rock, and all masses of both, were covered with snow or hoar-frost. The sun was sinking towards the Oder ponds. During the day, owing to the yellowish hue of the snow, shadows tending to violet had already been observable; these might now be pronounced to be decidedly blue, as the illumined parts exhibited a yellow deepening to orange. But as the sun was at last about to set, and its rays, greatly mitigated by the thicker vapours, began to diffuse a most beautiful red colour over the whole scene around me, the shadow colour changed to green, in lightness to be compared to a sea-green, in beauty to the green of the emerald.” (J. W. von Goethe. Theory of Colors, 1840/1985. Translated by Charles Eastlake. The M.I.T Press: Cambridge, Massachusetts and London).
From the forthcoming book Colour in the Visual World by Harald Arnkil. Publisher: Aalto University, Finland, 2013.
