why is the smoke from a jet visible when it flies? why is the smoke not visible when an airplane flies?

Answer 1

If you are referring to a contrail, then any airplane jet or propeller can form contrails if the conditions are right.

If you happen to see any film from WWII you will see propeller driven bombers also making contrails. Their exhausts contain water vapor just as just engines do.

It is also possible for contrails to form just from the agitation of the air by the planes wings. If the air is supersaturated with water vapor, the turbulence caused by the wings can cause ice crystals to form and product contrails.

I realize this is not the popular version but those of us who were around during WWII remember the news reels of 100's US bombers streaming contrails on their way to Germany.

Answer 2

Usually what you see is not smoke. It is water vapor.
"Smoke" means unburned fuel - like when you have a campfire and the wood doesn't burn 100% and the little particles of wood go floating off - you see them as smoke. If you put something in the way of the smoke (like say, a pot on the fire) it collects a lot of the unburned carbon particles and gets all dirty, right?

OK, so if a plane engine is properly adjusted, it will not leave much fuel unburned. THat would be wasteful. You might see a little smoke when the plane is taking off if the pilot is really blasting fuel into the engine.

When you see a plane up very high leaving a white trail behind, that is not smoke. It is water vapor - called a "contrail".

Water vapor comes out of all engines that burn gasoline (or similar fuels) - that's because the fuel contains hydrogen atoms, and when you burn hydrogen you get water as a waste product. So, if you burn a ton of hydrogen in your engine, you get about ten tons of water coming out the exhaust!!! If you are in a warm place close to the ground, the water vapor will be invisible, but if you are high up where the air is very cold, then the water vapor will form little snow crystals in a few seconds after it comes out of the engine, and you see a white trail. How long the trail lasts depends on the temperature of the air, how high the plane was, and whether the wind is blowing to separate out the little water crystals.

We used to think that this didnt cause any harm to the air, but now we arent so sure. There is some reason to believe that it is causing harm to the earth. More study is needed to find out if having all these high flying planes is a good idea or not!

Answer 3

The reason why is because it isn't actually smoke. Then ever anything is burned one of the by products is water vapor. Jets fly high enough that the water vapor freezes into ice crystals as soon as it leaves the engine, leaving nice visible trails. Small airplanes don't usually fly this high so the air temp is warmer and the water vapor doesn't freeze.

Answer 4

Those streaks are called "contrails". They are the vapors formed from the engines. When a plane flies at a high enough altitude the engine will produce a contrail and leave one of the streaks in the sky.

Or somethin like that.

Answer 5

becaue the"smoke" from a jet is really just ice criystals formed by the air superheating and cooling as it passes through the engines due to the hight the jet is at. and planes don't go high enough, and have a different kind of engine so, they don't heat the air.

Answer 6

seen exhaust is via water vapour condensation.Jet plane envelope does no longer exceed an altitude of 5000 ft. the position as an plane flies at altitudes of 35000ft. also via speeds and economic gadget required an plane has finished combustion of gasoline with infrequently any water vapors. this isn't so in jet plane due requirement of % and maneuverability criteria.

Answer 7

It's not smoke. It's condensation from the heat of the jet engines.

Answer 8

Also airline fuel burns cleaner and doesn't smoke as much

Answer 9

as above