Not every high-flying jet produces a jet contrail. Conditions have to be just right. That includes the altitude, temperature, and moisture at flight level. Jet contrails are usually produced at altitudes greater than five miles. However, if conditions during the Winter are extremely cold, they can be produced at lower altitudes. Temperatures must be colder than -40° Fahrenheit, which isn't that uncommon, even in Summer months.
Finally, moisture is needed (which is why these occur in advance of low pressure systems). Thunderstorms being produced "upstream" boost water vapor high into the atmosphere which then spreads along jet stream winds. As jet aircraft fly through this high-humidity air, more contrails are formed.
I've been asked how this affects climate and climate change. Jet airplanes are big polluters...there's no question about that! The Environmental Protection Agency reports 12 percent of all transportation-related emissions in the U.S. are from aircraft.
On the EPA's website, information concerning regulation of aircraft emissions ends in 2016.
As more people use airplanes for travel, more jet contrails are being produced. Studies show that these additional clouds are reflecting some solar radiation, possibly keeping afternoon temperatures cooler. However, as contrails are less likely to be produced at night, nighttime temperatures are trending warmer.
In a Facebook post that is more than a year old, this is what I got from the “chemtrail” crowd in just a few days. #ConspiracyTheories pic.twitter.com/7rZGg0spgS
— EricSorensen (@ERICSORENSEN) August 14, 2018
There are conspiracy theorists who believe the presence of jet contrails, which they call "chemtrails," is proof of nefarious activity. In a recent post on my Facebook page, I received more than 7,500 comments, mostly from people who believe I am purposefully lying to the public.
Conspiracies can last a long time because they seem plausible. And then when someone believes a conspiracy to be true, they often find different things to back up their original opinion instead of facts that are contrary. That's why those craving information should be diligent with what's been proven fact. Conspiracies travel faster than jet airplanes, around the internet with no scientific consensus or factual basis.
-Meteorologist Eric Sorensen