Let There Be Light!

PHOTOS: ROBERT FISCHER

Snow is frozen water, but water is transparent. So why does snow appear to be white? It’s all about the light. Unlike ice, snow contains countless tiny crystals. These reflect sunlight back and forth between themselves within the snow before beaming it back out and into the eye of the beholder as white light – itself made up of all the colours of the light spectrum.

The Inn river near Innsbruck. The X in the foreground is part of a bridge spanning the waterway.

The Wildspitze mountain in the Stubai Alps.

Light falls on rubber matting at the bottom of a ski lift.

Clouds offer little protection from the sun’s rays. In many cases they filter only 10% of UV light. Snow, on the other hand, reflects sunlight and can almost double its intensity. This can result in a phenomenon known as snow blindness, when the retina is burned by sunlight entering the eye.

Patterns blown into the snow by the wind and lit by the sun.

Thin clouds above the Stubai Glacier. Multiple exposures give this photo an almost surreal appearance.

Ski tracks in the snow on the Stubai Glacier. This photo was also taken using multiple exposures.

High up in the mountains the air is not only colder and cleaner  – the sun’s rays are also more intense. The reason for this can be found in the filtering function played by the air: the further light has to travel through the atmosphere, the weaker its UV radiation becomes. Travelling high into the mountains shortens the distance that sunlight has to travel. Per 1,000 vertical metres the UV radiation increases by up to 20%. That is why suncream and sunglasses are a must when out and about in the high mountains.

View of the Stubai Glacier.

A mountain stream.

Looking out through a cable car window.

Since the beginning of time, humans have associated light with joy and life itself. Indeed, light does have a range of tangible phyiscal effects. It simulates the production of vitamin D, influences the production of melatonin and is responsible for our day-night rhythm. The latter is regulated by receptors in our eyes which measure light levels. During the day the production of melatonin is suppressed – we feel fit and alert. At night the production of melatonin is stimulated – we feel tired and sleepy. That’s why doctors recommend taking regular walks in the fresh air in winter if you are feeling tired.

The Stubai Glacier.