2007-01-12 03:54:22 · 9 answers · asked by Anonymous in Cars & Transportation ➔ Aircraft
As air enters the engines of a jet, it is compressed and heated, then heated further as some of it is used in the cumbustion process. At cruise speeds, this heated air exits the engine at approximately 500 degrees Celsius. The ambient air temps at those altitudes can be -100 Celsius, so the exhausted air will cool very rapidly. The moisture condenses out and forms ice crystals, which can suspend in the air, as a trail, until the upper winds dissipate them.
If a plane is not leaving a trail, it is generally because either the upper air is relatively warm, or there is little moisture.
2007-01-12 05:03:31 · answer #1 · answered by lowflyer1 5 · 1⤊ 0⤋
Contrails are condensation trails (sometimes vapour trails): artificial cirrus clouds made by the exhaust of aircraft engines or wingtip vortices which precipitate a stream of tiny ice crystals in moist, frigid upper air. Contrary to appearances, they are not air pollution as such, though might be considered visual pollution.
As NASA states...
"Contrails only form at very high altitudes (usually above 8 km) where the air is extremely cold (less than -40 degrees C). Other clouds can form at a range of altitudes, from very close to the ground, such as fog, to very high off the ground, such as cirrus clouds."
2007-01-12 13:14:05 · answer #2 · answered by capenafuerte 3 · 0⤊ 0⤋
Contrails are condensation trails (sometimes vapour trails): artificial cirrus clouds made by the exhaust of aircraft engines or wingtip vortices which precipitate a stream of tiny ice crystals in moist, frigid upper air. Contrary to appearances, they are not air pollution as such, though might be considered visual pollution.
2007-01-12 11:57:01 · answer #3 · answered by Mr. KnowItAll 7 · 3⤊ 0⤋
Most of these answers are correct. Also remember that you can have contrails at lower altitudes as well. It matters more about the outside ambient temperature and the moisture density of the air, not the temperature of the exhaust of the plane. If it was about heat than we would not see them from the wing tips.
2007-01-12 20:03:57 · answer #4 · answered by Anonymous · 0⤊ 0⤋
As atmospheric conditions vary, such as the amount of moisture, the temperature and the wind speed, so the effect of an aircraft zooming through the air varies. Sometimes it causes contrails, other times not, sometimes the contrails disappear almost as soon as they're made.
In short, it the weather!
2007-01-12 12:06:33 · answer #5 · answered by Anonymous · 0⤊ 0⤋
if the air surounding is saturated with water vapor or very high in humidity then you will see what is called contrail but if the air is "dry" or less humid then you won't see the contrail.
tha's because when the engine is working it realeses water and if the air is really humid it can't absorb the extra water released from the combustion so the extra water will appear as a contrail which is exactly the way clouds are.
2007-01-12 22:26:24 · answer #6 · answered by TimTim 3 · 0⤊ 0⤋
happens when they fly through a cold pressure system. The hot air from the jet engines leaves this. Other answer was exactly right re: seeing ones breath in cold weather.
2007-01-12 12:02:43 · answer #7 · answered by shaker 2 · 0⤊ 0⤋
OMG I was just thinking of that yesterday! Someone told me it was a way of making clouds come in and 'force rain'. I doubt that. Anyway, I can't wait to see what answers you get!
2007-01-12 11:58:02 · answer #8 · answered by Caly 4 · 0⤊ 0⤋
its like when you can see your breath, its just cuz it below freezing way up there.
2007-01-12 11:56:54 · answer #9 · answered by jordan e 2 · 0⤊ 1⤋