Reuters – Aircraft condensation trails criss-crossing the sky may be warming the planet on a normal day more than the carbon dioxide emitted by all planes since the Wright Brothers’ first flight in 1903, a study said on Tuesday. It indicated that contrails — white lines of Vapor left by jet engines — also have big knock-on effects by adding to the formation of high-altitude, heat-trapping cirrus clouds as the lines break up. Read article
Editorial comment: Just to clarify: 1. While it is possible that there are so many jet aircraft flying – in cold enough conditions at commercial airliner height – that they criss-cross; they would do so in no particular pattern. However, regular patterns of criss-crossing have been observed, all over the globe – and they persist in the atmosphere for some hours; I’m not sure of the height which the aircraft fly at.
2. Cloud/atmospheric seeding (OYEN item) IS defined as weather modification; It has been going on for a long time by various private firms in US, at least. It requires moisture to be in the atmosphere to “seed” the rain/hail/snow. In some cases this is to avoid damage to homes or crops.
Chemtrails are different: They are often sprayed in completely fine/sunny conditions and persist for some hours – to what purpose is not widely known. After spraying over prolonged periods in some areas in the US. – it has been noted that considerable haze is persistent over that area.”
Please read the Historian’s very informative comments in the related article: Jet contrails spotted in Perth skies