White lines behind planes?

Question

Why do some airplanes leave cloudy lines behind them that can be seen in the clear sky?

Thanks

Answer 1

Search on the term "Chemtrails"... then make up your own mind.  Hint: Real contrails (water vapor) will dissipate quickly and will only be visible for a short distance (length depends on weather conditions but will not stretch across the sky!)

Answer 2

http://en.wikipedia.org/wiki/Contrail

try this

Answer 3

They're called contrails. It's the hot exhaust gases from the jet engines reacting with the cold air. It's a lot like seeing your breath on a cold day.

Answer 4

When you burn fuel, one byproduct is water vapour. When that vapour is released at high altitude, where it is cold, that vapour condenses into clouds behind the engines. They are called condesation trails or just contrails. They don't always do this because sometimes the air is slightly warmer or too humid or even to dry for the clouds to form.

Answer 5

they all diff.

Answer 6

Could be mosquito spraying, cropdusting, but I think you are thinking of contrails.. That is water vapor from the engine at or about 30,000 feet.  This is because the atmosphere is so cold at that altitude.

Answer 7

They are contrails.  They are water vapor.

Answer 8

thats called smoke

Answer 9

You mean contrails???

Answer 10

i think that's the smoke fuel burning,    

i think that's equal to us on the hwy, burning fuel out of the backs of our cars, trucks, vans. automobile .... somehow it looks more intense   idk.

Answer 11

The engines produce mostly CO2 and H2O (water vapor); when the plane passes through cold enough air the water vapor condenses into a mist.  The more humid the air, the longer they last; in hot dry air you won't see them at all.

Answer 12

They are contrails.  They are not water vapor.

Condensation trails.

They are clouds of liquid or solid water, not vapid water.

Water vapor is not visible.

Answer 13

Contrail

Answer 14

They are jets, not plane. They leave smokes as patterns in the sky to leave a message behind. Either that or thats the aftermath of the jet ripping through the clouds.

Answer 15

Jet fuel vapor. Like on a cold day you can see the vapor from a cars exhaust more then on a hot day. The hair is cold up where the planes are and the wide currents blow it to make it look bigger.  LOL

Answer 16

Shhhhh! your not supposed to notice that some planes leaves contrails that quickly dissapaite while others... hold on I've got to get the door.

Answer 17

I asked that when I was little. I always looked for a skywriter to write me messages like in cartoons. I think it has something to do with the weather/the temp. of the emissions.

I think.

Some planes have clean emissions and in cool weather it may not leave a lot up there. Just what someone made me think years ago.

I will watch your answers.

Answer 18

I have always wondred that too.  What I have heard it is soot from the hard working engines.  If you have ever seen a B-52 taking off you will see that there is tons of black soot behind it, coming out of the engines.

Answer 19

They are called contrails and are composed of water vapor crystals (ice) left behind the aircraft.  The conditions have to be right to support contrails which is why you don't always see them.

Answer 20

Condensation for temp changes in atmoshere

Answer 21

why do you leave skid marks in a white underwear, same concept.

Answer 22

The white streaks are typically called contrails, short for "condensation trail."

The rapid decrease in air pressure caused by the wing or by engine exhaust also causes a rapid drop in temperature, which then causes water vapor suspended in the air to condense into visible particles.  

The reason some planes do not appear to have contrails and some do is due to both the humidity in the air, and the temperature.

The more the humidity, the more apt an aircraft is to create a contrail.  Water vapor condenses when the temperature and dew point are very close (within 8 degrees).  (Think of a foggy day: everything feels wet.)  Increased humidity means the dew point occurs at a lower temperature than on a day when humidity is low.  

Aircraft at higher altitudes are more prone to contrails than those at lower altitudes because temperatures are lower at those high altitudes.  The lower temps usually mean the dew point "spread" is also less, which makes it easier to create water vapor, and hence, contrails.

Size and speed of the aircraft also affect contrail development.  The faster an aircraft goes, the greater the drop in air pressure as it passes through the air, and therefore, more contrail development!

Hope this helps.