What causes jets flying in the sky to leave white trails behind them? Why do some leave longer trails?

Answer 1

Water is a by product of combustion, so Jet engines dump a small amount of moisture into these high altitude skies. Occasionally, a really large thunderstorm will top out up there where the Jets fly, but it is unusual. Most of the moisture in the atmosphere is BELOW the clouds or in the clouds. There are a few cirrus clouds up high, composed of frozen ice crystals.
When this moisture condenses into "Con trails" it leaves those white stripes across the sky. The moisture will usually evaporate and the trails will disappear.

Answer 2

Yessiree, they are called contrails. Contrails are visible trails of condensed water vapor made by the exhaust of aircraft engines. As the hot exhaust gases cool in the surrounding air they may precipitate a cloud of microscopic water droplets. If the air is cold enough, this trail will be comprised of tiny ice crystals. Since the main components of jet exhaust are carbon dioxide and water vapor, the local increase in water vapor can push the water content of the air past the saturation point. The vapor then condenses into tiny water droplets or deposits directly into ice which is visible to you on the ground. Contrails are usually formed above 26,000 feet above sea level. The aircraft forming them can be military jets or a commercial airliner, or a business jet, since you are probably asking about the jets you see above 26,000 ft. altitude. They can come from any number of airports or military bases around the world and are going to some other airport. Pilots fly them. Contrails are not special, they form all the time and criss cross the sky. They will soon dissipate. Depending on atmospheric conditions, contrails may be visible for only a few seconds or minutes, or may persist for many hours.

Answer 3

These long trails that these airplanes leave are called contrails. 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.
Also, for every gallon of fuel burned, approximately one gallon of water is produced, in addition to the water already present as humidity in the air used to burn the fuel. At high altitudes this water vapour emerges into a cold environment, (as altitude increases, the atmospheric temperature drops) and the local increase in water vapour density condenses into tiny water droplets and/or desublimates into ice. These millions of tiny water droplets and/or ice crystals form the contrails.

Answer 4

These are called "contrails". The exhaust from aircraft engines is mostly carbon dioxide and water vapor from the combustion of the fuel (hydrocarbons) with the oxygen in the air. When conditions are right, the water vapour condenses into the contrail, which is essentially a long, skinny artificial cloud.

Answer 5

It is (as stated by another here) condensation of water vapor when hot exhaust meets cold air in a hurry. However the actual happening is that as the condensation actually forms it is just as quick frozen into minute ice crystals which is viewed by us on earth as a cloud. You will notice that depending on the time of year combined with the actual altitude of the plane those "contrails" may vary and at times don't exist at all.

Answer 6

The water vapor came out of jet engine get condensed due to very low temperature, it gets frozen in to minute ice crystals which is viewed by us on earth as a cloud.

Answer 7

When the warm air comes out of the jet engine it hits the cold air and turns into ice crystals,which hang around untill the heat from the sun melts them.

Answer 8

It can also be caused by wingtip vortices, which momentarily cool the air because of the drop in pressure. This, like many other questions posted here, can be answered at Wikipedia:
http://en.wikipedia.org/wiki/Contrail

Answer 9

contrails like a cloud when the hot air from the engines hit -30 degree temp then it forms a cloud so to speak

hope that helps

Answer 10

Most of the answers above are right on the money.

For some amusement, try this Google link. The Foil Hat Brigades are in full swing on this subject!

http://www.google.com/search?hl=en&q=chemtrails