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Why do airplanes leave a white trail?
Jets leave white trails, or contrails, in their wakes for the same reason you can sometimes see your breath. The hot, humid exhaust from jet engines mixes with the atmosphere, which at high altitude is of much lower vapor pressure and temperature than the exhaust gas.
How long do contrails last in the sky?
Persistent contrails can last for hours while growing to sev- eral kilometers in width and 200 to 400 meters in height. Contrails spread because of air turbulence created by the pas- sage of aircraft, differences in wind speed along the flight track, and possibly through effects of solar heating.
Why do contrails stay around for so long?
Contrails are actually a type of cirrus cloud. When the air is wet and cold enough the trails can stay around for a long time, and sometimes spread out.
Why does one plane have contrails and the other does not?
Yes, it’s really that simple. The reason that one plane makes contrails or makes contrails that persist, and the other plane does not, is that they are in different regions of the air. For simplicity, let’s refer to these regions of air as wet air and dry air, although the differences are a bit more complex.
Where do the contrails form in the sky?
The contrails start forming on the east, near the clouds where you have a higher humidity, and do not form on the west, where no cloud is present and you have higher temperature/lower humidity. I’ve often noticed that planes flying on more or less the same track, headed in the same direction leaves different contrails.
How long does it take for a contrail to form?
The answer is reasonably straightforward, but misunderstanding is common. To understand whya contrail can last as little as a fraction of a second, or as long as several hours, you need to understand whata contrail is, and howit forms. Here’s another question, which has the same answer: