[kach22i]

Laugh all you want, those steaks in the air do add up. Post 9/11/2001 when all flights were grounded weather data accumulated showed a change. NPR covered this more than once as it was related to climate change (once known as global warming).

I forget if the temperatures went up because more solar radiation made it's way down to the ground, or if temperatures went down because the cloud/vapor cover keeps heat in via the Venus effect. Apparently the up or down change caused by contrails was under debate until real data came in.

I did find the following website, sort of a mix of actual events and prevailing conspiracies all rolled up together.

Artificial Weather Revealed by Post 9-11 Flight Groundings
Artificial Weather Revealed by Post 9-11 Flight Groundings

Some boring science sites follow.

2002
Jet Contrails Alter Average Daily Temperature Range
https://www.sciencedaily.com/releases/2002/08/020808075457.htm

"We show that there was an anomalous increase in the average diurnal temperature range for the period Sept. 11-14, 2001," the researchers reported in today's (Aug. 8) issue of the journal Nature. "Because persisting contrails can reduce the transfer of both incoming solar and outgoing infrared radiation and so reduce the daily temperature range, we attribute at least a portion of this anomaly to the absence of contrails."

And still news a decade later using satellite data from different decades (30 years apart).


Jets’ contrails contribute to heat-trapping high-level clouds
By Anne Danahy
February 21, 2013
Jetsā€™ contrails contribute to heat-trapping high-level clouds | Penn State University

UNIVERSITY PARK, Pa. -- Condensation trails that airplanes produce mean not only a white-streaked sky on some days, but an increase in the amount of high-level clouds and, by extension, warming temperatures, according to a Penn State researcher....................

To address the question of whether there is any relation between jet contrails and trends in sky coverage, the researchers plotted the spatial occurrence of contrails identified on the satellite images for two time periods: 1977-79 and 2000-02. Sky cover data on clouds occurring at different levels has been collected continuously at National Weather Service stations. The satellite contrail and surface-observed sky-cover data was overlaid and separated according to high versus low frequencies of contrails............................

The researchers found that high frequencies of contrails didn’t equate to an increase in total cloud amount or an increase in low-lying clouds, but they did mean a significant increase in high-level cloudiness observed from the surface since about the mid-1960s.

Artificial weather is a stretch, weather affected by our activity - that's a given.

http://news.psu.edu/story/265650/2013/02/21/research/jets%E2%80%99-contrails-contribute-heat-trapping-high-level-clouds

Carleton’s previous research found that contrails affect the climate near Earth’s surface by reducing the daily range of temperatures (the warmest point during the day minus the coolest temperature at night). He and David Travis, from the University of Wisconsin-Whitewater, undertook a base study on contrails and surface temperature conditions after the Sept. 11, 2001, terrorist attacks, when there were no commercial jets in the air for three days. They found that the lack of flights led to an increase in the range of temperatures for the United States in general, and sub-regions typically seeing the highest frequencies of contrails (the Midwest and Northeast). The researchers concluded that jet contrails contribute to reducing the near-surface air temperature range.

Persisting contrails present the greatest impact on climate because instead of dissipating relatively quickly they linger, trapping heat beneath them. While contrails do block the sun to some extent, when they persist they also spread and become thinner, which means they don’t reflect as much solar energy away while still trapping heat.

“The net effect tends to be to warm the earth’s surface, rather than to cool it,” Carleton said.

This would be an interesting outcome - longer flights are the answer?

http://news.psu.edu/story/265650/2013/02/21/research/jets%E2%80%99-contrails-contribute-heat-trapping-high-level-clouds

A next step is trying to predict where and when contrails will occur so, when needed, planes could be rerouted around those areas to head off further aggravating the contrail impact on climate. Carleton noted that this is similar to the short-term rerouting of planes that already happens with severe storms.