Originally Posted by
beardy
... Sometimes the ice crystals persist, at other times they evaporate, dumping water vapour into the atmosphere, water vapour which in itself is a potent greenhouse gas.
...
Let me explain how those contrails form. The aeroplane does
not emit that water to forms the contrails, The aeroplane disturbs moisture
that is already in the air causing it to condense and form the contrail. Watch on days where there is a very dry upper atmosphere, You can easily see on those dry days how short the contrail 'tails' on aeroplanes are. Hopefully that has helped you a bit?
Regarding the comment:
I can assure you that there are (in normal circumstances) many, many, many more contrails on the daytime side of the earth than on the night-time side of the earth. (Been there, seen that!)
... you say:
Originally Posted by
beardy
...
Have you never wondered where they went? And what happened to the water vapour?
...
Ummm...!!
- There
- are
- less
- contrails
- at
- night
- ...
- because
- there
- are
- less
- aeroplanes
- at
- night.
Just try listening to any ATC frequency at 2pm and compare with 2am.
Those contrails never 'went' anywhere, they were never created!
If you are worried about global temperature rises and ice melt, we need more airliners flying!!