Daylight as Information - Light as information

The sky has always fascinated me, it is constantly in flux through changing weather systems and sun movement, providing us with a constant stream of information on what the weather is doing and what time of day and year it is. A large part of this information is communicated through colour and our understanding of what different colours signify. Some photographs of skies taken at different times and dates can be found on the skies on the photography page.

In August 1999 a large part of the world experienced a total solar eclipse (the full extent of the eclipse can be found here). I was lucky enough to be in Alderney in the Channel islands where we experienced the full eclipse for nearly two minutes. As the sky turned slowly orange, getting darker, the confused birds started to sing and a similar confusion came across us. Even though we knew the eclipse was going to happen and the sky was going to get dark we weren't prepared for the strange orange twilight that ensued. Whilst our brains knew that it would get dark there was a disparity between our expectation and the actual experience. The experience had a much greater impact on my perception than I thought. The immediate information from my eyes was telling me it was evening and getting towards night very fast and my body seemed to fall into the routine of relaxing and preparing for sleep, in the same way that the birds began to sing.

This highlights the difference between the empirical understanding of the observed phenomenon, based solely on what is observed, a scientific understanding and an archetypal knowledge of phenomena. It is one thing to look at the sky and see it change from blue to orange to black but another to know it is a solar eclipse caused by the moon blocking our view of the sun. It was only because we had a notional scientific knowledge that the sun was going to disappear that we didn't think that night had come early all of a sudden or the world was going to end. These ideas were introduced by Goethe whom I will introduce properly In the next section 'Light as Material'. This links back to the decision by Turrell to hide the working of his installation. If we had been alive a few millenia earlier an eclipse might well have struck us with fear, but an understanding of how an eclipse happens informs our peception and can change our reaction from fear to awe. I write 'can' because these reactions are subjective and are dependant on a whole range of other factors, including belief and faith, as well as understanding.

Understanding the Changing Colour of the Sky

What makes the sky blue and the light to change colour? The answer lies in the absorption of colour by particles in the atmosphere. The red end of the spectrum is more penetrating than the blue end so at a low angle only red light gets through, when the sun is higher in the sky the light is scattered by the particles that make up the atmosphere and blue is scattered more than red. So when a beam of white light travels through the atmosphere at sunset or sunrise all the blue is scattered and only the red reaches your eye. This phenomenon can be illustrated by creating a milk and water solution and shining a bright light through it. The milk particles do a similar job to atmospheric particles scattering blue light and letting red light through.

Having spent a large part of 18 months in a studio with no windows the requirement of information from the sky and daylight in general has become particularly pertinent. Without the constant stream of information a window with a view affords, days pass by intangibly and you are left wondering where the time went.

A quick note on Functional Daylighting

The redirection of sunlight for daylighting in architecture has a long history. From 1896 Luxfer Prisms (fig 3) were used to refract sunlight into buildings. A good source of information and history on the application of glass prisms to architecture can be found at glassian.org. More recently heliostat driven systems, which use optic fibres to transmit sunlight have become commercially available. I don't want to spend much time on these type of daylighting systems because I'm more preoccupied with issues of perception and interaction. There is already a wealth of information on daylighting systems on the web and elsewhere.

Light as material: What is Light?