Either by day or a little after sunset, in fine weather, a little, light, long-drawn cloud is seen, like a long very straight line.
- Aristotle, Meteorologica, 340BC
Not every long straight line in the sky is a contrail. Here Aristotle suggests it’s “a sort of wave-mark in the air”. Basically an isolated row cloud, low on the horizon.
Aristotle’s take on the weather is very interesting. He has quite an extensive section on atmospheric optics – halos, sundogs, etc. Pretty advanced for 2347 years ago.
There actually WERE contrails before airplanes were invented, just rather rare, and of a different sort. Here’s an image of one from 1751, showing how it formed, and how it was distorted by the wind.
and one from 1866. (drawn by an observer in Cardiff, England, for an event on November 14, 1866, an event that was visible for 10 minutes)
These are meteor trails, which could be comprised a disintegrating meteor, but also of clouds precipitated by the dust and pressure changes. This type of contrail has been around for billions of years.