Revolving through the Megacosm

This is a collaboration between myself and scientist Geoff Wyvil for the Art + Air project, curated by Pam McKinlay in collaboration with University of Otago, NIWA and the Dunedin School of Art, Aotearoa New Zealand.

Louise
My practice is fundamentally concerned with the night sky and how our connection to it is fading through light pollution. This project has challenged me to think more about our atmosphere itself, rather than its transparency. 

Air tides are something that I hadn’t explored before, and learning about them from Geoff inspired me to think about the atmosphere being pushed and pulled as it travels around the solar system with our planet and as the solar system spirals around the Milky Way. All of the forces at play on our planet have created a semblance of balance over billions of years and this thin blue line is all that exists between us and the brutality of the vacuum of space. This cosmic wisp of gases makes our world a garden of life, instead of an inhospitable, dangerous place impacted by solar radiation, cosmic radiation, massive temperature fluctuations and meteorites. 

Our ever evolving blue marble has travelled around the Milky Way 18 times since its formation 4.5 billion years ago, whilst these earthly weather systems, influenced by our star, our satellite and our neighbouring planets have carved and shaped our world and everything that lives within it.

Geoff
What can physics tell us about the weather? We live on an oblate liquid spheroid which has a thin solid crust, partly covered by water and the whole wrapped in a layer of air. What are the driving forces?

Our world has a moon whose mass is about one eightieth of the earth’s. We say that the moon orbits the earth but it would be more accurate to say that the earth and moon swing around a common centre. On the surface of the earth, gravity appears to be least when the moon is overhead or on the opposite side and most when the moon is near the horizon. This causes the familiar two tides per day gradually getting earlier through the lunar month. The tide is really the difference between the sea-tide and the smaller tide in the earth’s crust which also moves up and down. There is an even larger tide in the air above. 

Our weather is driven by a number of forces acting in cycles. The daily heating and nightly cooling together with these tidal forces are the main ones. The slower, annual shifting of warmth from south to north and back causes the monsoons.

It is the response of the atmosphere to these cycles that produces the chaotic complexity of our weather. Movement in the sea is altered by resonance of waves generated by the shape of the seabed. Winds are disturbed similarly by mountains and valleys.