Contrails? Sometimes there, and sometimes not

Hello! I was recently taking photos of planes, and I usually try and find them by their contrails/vapor trails. Usually when they fly over my house, there are contrails, but today none of them had them. Why is that sometimes they are there, and sometimes they are not? Does it have to due with weather? Or altitude? Sorry for my confusing wording, and let me know if this is already a topic. Thanks!

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Exhaust contrails usually form at higher altitudes (often above 26,000 ft), where the air temperature is below −36.5 °C. They can also form closer to the ground when the air is colder. It really depends on the current situation.


I believe those planes could be:

  1. dumping fuel
  2. making some lift
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  • Contrails that disappear rather quickly indicate areas of moist air. In other words, there’s water vapor invisible to the naked eye suspended in the atmosphere.

  • Contrails that stick and linger around for a longer duration indicate areas of drier air.

More info abound different types of contrails can be found below:


Oh, Ok. That makes sense to why I didn’t see any today as it was quite warm. Thanks for the clarification!

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Something to remember that in cruise, you’re looking at temperatures in the -50 to -55C range… even if it’s say 30C (80’sF) on the ground. Contrails will still form. The factor that were mainly looking at is the water vapor content in the air 6-7 miles above us. 🙂


Sometimes pilots forget to switch them on:



I heard a DAL A330 going to AMS fly over my place last night and that was the first thing I looked for was contrails. None.

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