09
Feb
10

Catastrophic Optics and Brocken Spectres

Catastrophic Optics and Brocken Spectres

These are 2 visual distortions that have fascinated me over the last few months.
During my residency last year at the NPLab I was introduced to the phenomena of Catastrophe Optics – great name!
Have you ever stared into a cup of tea or coffee and noticed the play of light on the surface or the patterns light makes on sand when seen through water or the sun sparkling on a lake or pool?
These are delicate patterns are the optics of nature, the physics of light, otherwise know as interference diffraction phenomena.
The mathematicians Thom and Arnold discovered that there are only 3 forms that these departures from symmetry (known as caustics) take – the fold, the cusp and the swallowtail. To see these shapes – http://www.phy.bris.ac.uk/people/berry_mv/pictures/poster1.pdf
I never quite found a way of incorporating these sculptural twisty geometrical shapes into my artwork but as someone who has spent a lot of time painting sunsets over water I find the idea that something as apparently illusive and transitory can be ‘pinned down’ scientifically and analysed. The image below is a painting I did of the Marshall Islands with the sun shining through the clear tropical water.

The second visual distortions are called Brocken Spectres – wonderfully ghostly phenomena sometimes witnessed by mountaineers when the conditions are just right. The examples below are closer to the earth – misty forest and in the headlights of a car.

 

A Brocken spectre (German Brockengespenst), also called Brocken bow or mountain spectre is the apparently enormous and magnified shadow of an observer, cast upon the upper surfaces of clouds opposite the sun. The phenomenon can appear on any misty mountainside or cloud bank, or even from an aeroplane, but the frequent fogs and low-altitude accessibility of the Brocken, a peak in the Harz Mountains in Germany, have created a local legend from which the phenomenon draws its name. The Brocken spectre was observed and described by Johann Silberschlag in 1780, and has since been recorded often in literature about the region.

The “spectre” appears when the sun shines from behind a climber who is looking down from a ridge or peak into mist or fog. The light projects the climber’s shadow forward through the mist, often in an odd triangular shape due to perspective. The apparent magnification of size of the shadow is an optical illusion that occurs when the observer judges his shadow on relatively nearby clouds to be at the same distance as faraway land objects seen through gaps in the clouds, or when there are no reference points at all by which to judge its size. The shadow also falls on water droplets of varying distances from the eye, confusing depth perception. The ghost can appear to move (sometimes quite suddenly) because of the movement of the cloud layer and variations in density within the cloud.

The head of the figure is often surrounded by the glowing halo-like rings of a glory, rings of coloured light that appear directly opposite the sun when sunlight is reflected by a cloud of uniformly-sized water droplets. The effect is caused by the diffraction of visible light.

Fabulous! The science and beauty of these images is justification (if it was needed) for the inclusion of the occasional ‘ghost’ or presence in my paintings. The glorious neutral colours in the first image serve to emphasise the subtle rainbow effect and this may well find it’s way into the new body of work that I am currently working on. At least it will – as soon as the temperature in my studio rises above 5 degrees (and that’s with the heater on).

Recent noteworthy experiences
Nudity in Epsom
Cold misty morning loaded up the mini with art materials, my trusty assistant and navigator Steve, and model – Hugh Barnden who is also an established artist in his own right. We arrived at the Royal Automobile Club – an old stately home well off the main roads and set in a beautiful landscape of rolling hills and golf course. We had been hired to put on a one-day Life Class for the members and what a delight it was!
The class took place in the sumptuous Derby Room with heavy velvet drapes and ornately framed oil paintings of horses lit by chandeliers. It was without a doubt the best environment I’ve ever taught in, fabulous lunch, delightful participants and all really well organised by the RAC staff. The environment echoed the dignity and gravitas that was once awarded to ‘Life Drawing’ – according to my more elderly art tutors – students would have to spend their first years drawing only from plaster/marble figures until they could show sufficient skill to be allowed the privilege of entry into the hallowed ‘Life Room’ where a roaring fire and thick curtains would protect the naked model from draughts.

Below is a painting done from the reference photos – it was shown of several occasions but no one really recognised what it represented so I’ve since painted over it:

‘Spectre’ – Lee Campbell

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1 Response to “Catastrophic Optics and Brocken Spectres”


  1. 1 Barry
    February 15, 2010 at 10:36 pm

    Many years ago I was fascinated by the name of a race horse I felt obliged to have a small wager on. “Ring Around The Moon”
    It was many years later again when I witnessed the phenomena for only the second time.
    “Catastrophe Optics ” helps me understand how it happens. Thanks for that.
    (Dos’nt explain why the horse did’nt win tho!)


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