Many people are not aware of the difference between con-trail, chem-trail and high cirrus clouds. There are chem-trails and this is publically known for years, Since the 1960's and before they seeded clouds to inhance rainfall usually using Silver iodine with dry ice. One way to define the difference is the wind will blow in one direction and the clouds should be in that one direction. Since the early 1900's they have been playing up there. Also, many are unaware of mans ability to influence the weather and when deep experimentation began, that date, August 1976 when Nasa published their inadvertant modificaqtion of the weather, you can see the article here that stimulated the science communiity into its potential. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770011718_1977011718.pdf Facts are, they have seeded, they do seed, but what are they using? If it is no danger, then why do they deny doing it? Two planes at the same altitude both using jet fuel, one leaves a 40 mile trail that resides for hours, the other has nothing. We will see tomorrow as the temperatures drop to -20 tonight, if there is a cloud or haze in the air, then it was put there either by emissions or another source...but it won't be natural.