http://contrailscience.com/chemtrail-myths/#comment-5185

We are seeing HUGE contrails forming at levels as low as 25-30%. Can you explain this via the “normal” explanation?

There needs to be a high Relative Humidity level in the upper atmosphere where commercial aircraft fly to form any sort of “persistent contrail”. This is generally regarded as a RH of %60 and above. Even then, the “persistent contrail” will simply break apart and fade away after an hour or so. This is not the case with these particular aircraft contrails which hand in the air and form a thick “haze” over the area until blown away by the wind.

Which is directly contradicting known science. For example, see the Encyclopædia Britannica article on vapour trails (contrails):

Contrail, streamer of cloud sometimes observed behind an airplane flying in clear, cold, humid air. It forms upon condensation of the water vapour produced by the combustion of fuel in the airplane engines. When the ambient relative humidity is high, the resulting ice-crystal plume may last for several hours. The trail may be distorted by the winds, and sometimes it spreads outwards to form a layer of cirrus cloud.
vapour trail. (2007). In Encyclopædia Britannica.Retrieved May 4, 2007,from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-9074829

Also see “A Field Guide to the Atmosphere“, by Schaefer and Day, 1981:

“Sometimes [contrails] are ephemeral and dissipate as quickly as they form; other times they persist and grow wide enough to cover a substantial portion of the sky with a sheet of cirrostratus“ (Page 137)

NO ONE who has more than a passing interest in this subject denies persistent contrails.

Listen up…

It should be stated, however, that this water vapor would have to be discharged into air which was very cold and nearly saturated.

Note the “nearly saturated” comment. We are seeing HUGE contrails forming at levels as low as 25-30%. Can you explain this via the “normal” explanation?