What are the white lines left on the sky by jets?

Question

They are straight lines on the sky that very slowly goes away. At times there are many of them all over, and no one seem to really know what exactly they are. Many theories but nothing concrete. Help?

Answer 1

Contrails.

"The condensation trail left behind jet aircrafts are called contrails. Contrails form when hot humid air from jet exhaust mixes with environmental air of low vapor pressure and low temperature. The mixing is a result of turbulence generated by the engine exhaust."

Answer 2

They are called 'Contrails' or 'Vapour' trails. They're just condensation trails or artificial clouds made by the exhaust of aircraft engines or wingtip vortices which precipitate a stream of tiny ice crystals in moist, frigid upper air. They're behind one of the reasons why we have a lot of pollution.

EDIT: There really is no 'purpose' for the contrails. They are necessary to give off exaust. Like a car. It's the way the jets run and trust me, creating contrails is not just for fun. The last thing we need to make is more pollution.

Answer 3

Artificial clouds, basically.  They're vapors left over from the combustion process in the jet engines.  They're all the same, but sometimes they hang around longer because of weather conditions.

Answer 4

they're called vapor trails.

Answer 5

ice.

well, sort'a like artificial snow.

it's really cold.

the jet engines create H2O and CO2.

you can't see the CO2.

but you can see the H2O.

and that that altitude, it freezes pretty quickly.

they're called contrails.

they eventually just evaporate.

how long it takes to do that depends on how wet the air is.

the drier, the more quickly they disappear.

Answer 6

Vapor Condensation Trails  

Answer 7

No, these are not typically one man jets. They're commercial aircraft carrying either passengers or air freight, and sometimes they're military aircraft. Any time a hydrocarbon (such as jet fuel) is burned, the waste products are always carbon dioxide and water vapor. The water vapor is quite hot, because it just came out of a jet engine, and the air around it is quite cold due to the high altitude. For this reason, the water vapor condenses and becomes visible, exactly like a cloud. You can actually watch these condensation trails being formed as a plane flies over you, if it's up high enough. Down lower, the air is too warm for the trails to form. I hope this clears up the mystery for you.

Answer 8

parang un ung lumalabas sa tambutso ng sasakyan.. mas marami nga lang sa jet kasi nga malaking enerhiya ang kinkailangan nila dun.. parang sa spaceship din..

Answer 9

jet f**t!

Answer 10

They are vapour trails, exhaust from jet engines. Like clouds, they gradually dissipate.  

Answer 11

vapor form extra fuel they let it off before they land.  

Answer 12

contrails that eventually dissipate like clouds.