why there is smoke like behind the tail of jet aeroplanes?

Answer 1

At altitudes above 30,000 feet, there are contrails produced on the wing of aircraft.

Contrails are actually cloud, not smoke, and they are produced because at 30,000 ft or above, the air is cold enough to condense to produce clouds.

Wikipedia has a good article here: http://en.wikipedia.org/wiki/Contrail

Hope this helps!

Answer 2

I believe that you are referring to contrails, here is a description:
There you are laying in the grass gazing up into the sky looking at the white puffy clouds, as kids I am sure we have all done this. You see some that are white and puffy and others that are thin and spread out. Then you see an airplane coasting through the sky, leaving long cloud like trails behind. That cloud like trails are known as contrails.

There seems to be a lot of interest in contrails, people wanting to know what they are, how and why are they created, and some people even think that its chemtrails or chemicals being dropped out of aircraft as they fly high above. Really there is a very simple reason for the creation of contrails.

Commercial airlines fly at very high altitudes, usually ranging between 30,000 and 40,000 feet. They fly at the higher altitudes because the aircraft are more fuel efficient at that level. As you go higher in the atmosphere the temperature starts to drop and becomes increasingly colder and colder. So when the humid exhaust from the engines mixes with the air at the high altitudes the contrails are created. The turbulence from the engines actually causes the two to mix together. An example of this on a very small scale is when you breathe into cold air and you see your breath.

Answer 3

There are two types of contrails (both have been covered here):

1) compressed air flowing over an airfoil.

2) (most likely what you are talking about, seen in the air behind commercial aircraft) Condensed air.


Most people are right about the hot exhaust coming from the engine condenses causing it to form water vapor seen as clouds, but most people don’t realize that there is fine particulate matter in the exhaust and that is what the water vapors in the air are actually condense on to.

Answer 4

Basically the engines introduce water vapor into the atmosphere. If the atmospheric conditions are right ice crystals develop (not smoke). Since the air is so cold up there, this air can become saturated and the "left over" water condenses forming those ice crystals (basically man made clouds).

Answer 5

It isn't smoke. It's a contrail. Very much like a cloud, and it's caused by the hot exhaust and the cold air.

http://cimss.ssec.wisc.edu/wxwise/class/contrail.html will give you more on it.

Answer 6

They aren't smoke they are clouds known as contrails.

This is ambient air temperature is so different from the temperature of the exhaust gasses that they immediately condense causing a cloud like formation.

Answer 7

The old adage 'there is no smoke without fire' comes to mind.

After all within a jet engine, there is fire - after the intake and compressor.

Answer 8

its not smoke - its either contrails or water vapour

Answer 9

the pilot is smoking crack!