Now, I know I am getting into deep water here, or maybe that should read ‘thick air’ but in talking about breath, wind, air, and so on thought must be given to atmosphere. We all know what the atmosph…Wait. Do we? Can you point at it? Can we see it? Can you measure it? Ah, yes we can apparently.
The word ‘atmosphere’ is of 17th century origin and has come into English via the Latin atmosphaera which is derived from the Greek atmos (vapour) and sphaira (globe). Technically the atmosphere is the gaseous layer that envelopes a planet. The earth’s atmosphere consists of a number of sub-layers: the troposphere is nearest to the ground (and has the planetary boundary layer at its base) and has a ‘depth’ of between 7 and 17km (shallower at the poles); next is the stratosphere taking us up/down to about 50km (and contains the ozone layer from about 15 to 35km); then the mesosphere (extending to 85km); the thermosphere (which includes the ionosphere) all the way out to 690km where the exosphere takes us out to about 1,000km above the earth’s surface. Here the exosphere meets the magnetosphere.
Of course, our personal compasses will already be confused by the vast scales described here before we even consider the language to describe these scales. Is it height, or depth, or thickness, is it out, above? Whilst the upper portions are evidently vital to life on this planet in terms of this research it is the troposphere which is most relevant. Troposphere derives from the Greek tropos (change or turn) and sphaira (globe). The change name-checked in the etymology is the shifting forces and pressures which lead to our everyday weather.
The planetary boundary layer constitutes the first few hundred metres to 2 kilometres of the troposphere up from the earth’s surface. This is the section which concerns the day-to-day experience of most mere mortals. This is where most flight takes place (although jumbo jets and some birds fly higher up in the troposphere at around 7 to 10km above the planet’s surface) and so is the limit of our lived experience on this planet. As mentioned above these layers vary in thickness depending upon their relation to the earth’s poles and also, as can be seen in the adjacent image (and the Planetary Boundary Layer limit), the shape and depth of the layers are effected by landform, weather and so on.
So far, so good. But in this introduction to atmosphere we have not even mentioned Ingold’s “weather-world” or Böhme’s take on atmosphere as “the fundamental concept of a new aesthetics.”1 Anon.
1. Tim Ingold, Being Alive (London: Routledge, 2011), 96-97 and Gernot Böhme, “Atmosphere as the Fundamental Concept of a New Aesthetics,” Thesis Eleven 36; (1993): 113-126, doi: 10.1177/072551369303600107.