Naked Science Forum
General Science => General Science => Topic started by: Simulated on 29/03/2008 01:52:09
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I mean at my house every day you can see loads of jets just "playing around". They have to burn a lot of fuel just on take off plus all the time they spend just around out there.
Granted there ain't as many of these as there are cars, but still.
Thanks Sim [:)]
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yes they do.
jet fuel is a carbon based fuel, and burning it produces carbon dioxide.
a much higher proportion of the carbon dioxide we produce as a society still comes from burning coal however.
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in fact, the estimate is that aviation accounts for 11% of the greenhouse gas emissions caused by the transportation sector in the US (the majority of the emissions coming from cars).
and overall, the burning of liquid fuel (which almost all transportation does) only accounts for thirty something percent of the overall greenhouse gas emissions, the majority, as i said coming from solid fuels.
so even in america, where people fly more than anywhere else in the world, jet engines still only account for a small percentage of CO2 emissions.
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The question is not only how much CO2 they produce, but the effects of the vapour trails, and NOX emissions.
The vapour trails themselves might possibly even have a cooling effect, but they could have an impact on the ozone layer (maybe someone else can say more precisely on that).
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Yeah that's true.
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Contrails are far more complicated than "you" may think, they are also an indication of the weather conditions.
When we see contrails (cirrus clouds) this would show us that the air in the upper troposphere is moist, if there are 'several' contrails this can also indicate that evaporation is inhibited and that a front is approaching. The shape and width of the contrails will tell us how the upper winds are moving.
Since contrails are cirrus cloud, and like all cirrus cloud, they absorb, scatter and transmit a high proportion of incoming shortwave and outgoing longwave radiation, they reduce the range of daytime temperatures.
What effect does this have on climate change, if any? Well, this is not fully known and like all things there are camps on both sides. Although one often quoted example is, that after the attacks of9/11 when all air traffic was grounded, and so there were no contrails, the range between the daily min and max temperatures increased by over 1 degree c.
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Wow.