Just been trying to get a feeling for "parts per million" as this is discussed a lot on this thread - and what is apparently being measured.
1 part per million - by weight, what is it?
Well, the weight of the atmosphere causes pressure, and sea level pressure is about 1,000hPa = 100,000N/m2 so that means about 10tons of air above each square metre. (That makes sense because 1m3 of dry air weighs about 1.2kg at sea level, so without allowing for declining pressure, thats 8,000m - so if the air spreads up to 20-30km before "fading out" that makes sense). Thats 10million tons above each square kilometre.
The weight of air above the UK, surface area, 250,000km2 must therefore be 10million times 0.25million tons = 2.5 trillion tons. (2.5 thousand billion tons)
So, if the ash were 1 part per million, and were spread uniformly throughout the air above the UK, the ash in the UK air would weigh 2.5 million tons.
Similarly the whole of Europe is 10million km2, 40X UK so there is about 100trillion tons of air above Europe. 1ppm would be 100 million tons.
Some other points:
1 ton per second of ash generation means a million tons every 12 days
The first three days of the eruption on 14 April 2010 at
Eyjafjallajökull. generated about 750 tonnes / second on average - so thats about 200 million tons errupted in total so far
If spread uniformly over (just) europe that would be 2ppm
Obviously its not spread uniformly, has also spread over the atlantic and russia.
Can anybody provide a number for the mass of air passing through a typical (e.g. A320) jet engine per hour of flight?