Originally posted by Bangin
HowardRoark, thanks for your input.
I feel as if these were being made for a reason. I haven't established a viewpoint as to why, but I'd love to know.
I saw multiple aircraft in the sky (at the same time) and their flight pattern seemed irregular. Why does this 'normal' occurrence seem unusual to
me? It's not happening today, nor did it happen yesterday.
I certainly do not know much about aviation, but I know enough to recognize an irregularity in the sky. By the way, I'm an avid sky watcher.
Trail formation is dependent on weather conditions. In general contrails will form at high altitudes based on the following conditions
Temperature. At a typical airline cruise altitude, it is around -40 or colder.
Relative humidity with respect to ice and supersaturation: This is the key parameter that determines if a contrail will dissipate shortly after
formation, it will persist, or even if the conditions are right, if it will grow.
Moisture supersaturation happens quite often at high altitudes, especially prior to the passage of a weather front. What happens is that
moisture-laden air is lifted up and cooled by the normal weather dynamics. Because this air is actually rather clean, there are insufficient
particles present to allow the super saturated moisture to condense (or actually freeze) into ice crystals (as in a cloud)
When a jet passes through this air it does three things, it adds even more moisture (water is a principle component of jet exhaust), it adds a
concentrated swath of particles (unburned or partially burned fuel and soot), and it disturbs the air by its passage causing wake vortexes that
persist for a while after the plane has departed.
These three things are why contrails form and persist.
Why do you see the one day and not the next? Because the atmospheric conditions are different, that is why.
The right conditions happen more often in winter than in summer, so keep watching.