To suggest things that do not meet this basic criteria is equal to masturbation. It may feel good to you, will not produce any tangible results, and you may be embarrassed if you get caught.
Since it has to do with any number of factors, how do you gents propose to define the contrails altitude?And condensation streaming from wingtips in a high G turn is a totally different animal.
+1Clouds also depend on a lot of things yet we have them. HTC can set specific weather for the whole arena that would enable them.
Is it really that high up the list?