Originally posted by Imagrunt:
Of course, these "contrails" did not evaporate like the ones I remember watching as a child, and by the time we neared L.A. the sky had been criss-crossed and transformed from cloudless to completely obscured.
Being a retired Air Force weather forecaster, I think I can explain that one. "Contrail" is short for "condensation trail," phenomenon caused by the warm exhaust mixing with a large amount of ice crystals in the upper troposphere. (Some people think this is jet exhaust; it isn't. In fact, contrails were the bane of 8th Air Force bombers during WWII. Who needed radar, when pretty little contrails were pointing right at our bomber formations?)
The meteorological conditions for contrail formation is exactly the same as the meteorological conditions for cirrus type clouds. If you notice from the photos above, there is already a layer of high clouds where contrails are at. This is natural.
Sometimes contrails form at the same time the high clouds are forming. When this happens, the contrails will persist longer, and appear to steadily thicken and grow in size. It is not unusual for contrails to appear to turn gradually into cirrostratus. This happens because the same meteorological conditions are required for both. it is
not an indication of "chemtrails" or whatever other theory some people are putting forth. it is a naturally occurring phenomenon.
Strangely enough, the advent of "stealth" technology meant that Air Force forecasters had to once again sharpen their skills at forecasting contrails. A billion-dollar stealth bomber that leaves a contrail ain't real stealthy.
Onward and upward,
airforce
