Hypoxia and Medicine - What is the kind of smoke,that airplanes emit while in high altitudes?

What is the kind of smoke,that airplanes emit while in high altitudes?

I just wanted to know the proper term for the "smoke" that jets release in high altitudes?Why is this so?

Public Comments

contrails. it is condensed water.
What you're referring to isn't smoke, it's water. Called contrails or sometimes called jet trails. See the link below for an explanation.
its a kind of chemistry after that u can see a drops of liquids will appear
it's steam - water vapour the fossil fuels contain two major energy producing elements> carbon and hydrogen. burning carbon produces carbon dioxide (or carbon monoxide in the lack of oxygen) burning hydrogen produces water vapour. the exhaust gases contain portion of CO2 and portion of H2O. once the exhaust gases cool down enough, saturation reaches 100 percent and water vapour condenses (or in the case of high altitudes, resublimes into ice needles). to see a SMOKE of exhaust, watch MiG 29, F4 phantom II or taking of C 130. the brown trail behind, it's real smoke.
Chemtrails.
Water Vapour?
It's not smoke... They are called contrails, and are actually composed of condensed water vapour. They are formed when the hot gases emitted by the aircraft engines heat up the surrounding air very quickly, so water content in the air is instantly vapourised...Once this air cools enough, the water vapour condenses into tiny droplets of water that remains suspended in the air.(just like clouds).if the conditions are right, the water droplets may also freeze into minute ice crystals...That's how contrails are formed...
Contrails. They are condensed water vapor when water enters a jet engine and leaves at or near 100% humidity which can happen at high altitudes since the air is very cold. If you imagine water condensing on the side of a ice drink it's a similar process. Since the air at high altitudes is already very cold, when it gets mixed up by the jet engine it condenses, since the water vapor needs some kind of surface to condense on.
it is just a mini cloud made from the engine.