[Arthalion]

Yup, I hate to agree with the environuts, but anyone who spends any time outside at all should be familiar with this. There have been days that I've walked outside and literally seen cirrus clouds stretching horizon to horizon as the contrails from passing jetliners have widened from the winds and run together (the area I live in lies beneath the flight paths of four international airports). If anyone here is going to tell me that man-made clouds up to a hundred miles wide DON'T affect the weather, I'm going to tell them they're nuts.

[John H K]

Well, what people used to insist was that those persistent cirrus were CHEMtrails comprised of evil gubbmint experimental chemicals; I notice that idiocy seems to have died down, thankfully.

It's a simple matter of the combo of a variety of atmospheric conditions with jet aircraft exhaust.

[usurper]

If anyone here is going to tell me that man-made clouds up to a hundred miles wide DON'T affect the weather, I'm going to tell them they're nuts.

OK lets suppose for the moment that is true. Do you believe that it follows that the resulting clouds contribute to GW?

Based on my 42 years of astute observation, increased cloud coverage reflects solar radiation and cast shadows thereby cooling the earth’s surface and air temperature. This is why I curse clouds on all golf and water skiing days. If it is as you suggest and aircraft are responsible for ruining my weekends, then I will join you in cursing them.

[Don Corleone]

If anyone here is going to tell me that man-made clouds up to a hundred miles wide DON'T affect the weather, I'm going to tell them they're nuts.

They don't and I'm not. Those "clouds" are not thick enough to intercept even a tiny amount of energy going up or down. They cover such a small proportion of the total sky that they are statistically insignificant. Junk science... run amok in search of a financial grant!