When humidity is high in the upper atmosphere, persistent contrails can cover much of the sky. In addition to being bad for stargazing, they inhibit radiational cooling at night. This effect is suspected to be a minor factor in global warming.

Tony Flanders

I was in the country last weekend, but I wasn't expecting to do any stargazing. The weather forecast wasn't promising, and as evening approached on Saturday, the sky was criss-crossed with persistent contrails (see picture at right).

When I went out to check the sky around the end of nautical twilight, my first impression was that the clouds had gone and the stars had come out. But after I'd dark-adapted for a few minutes, I realized that something was wrong. Although the sky was completely cloudless, there were nowhere near as many stars as there ought to be that late in the evening, and even the brightest stars lacked a certain vibrancy. But as I've said before, stargazers in the eastern U.S. can't afford to be picky. Rather than hauling out my 12.5-inch scope, I decided to compromise and use my 15×70 binoculars.

It turned out to be a surprisingly gratifying night of stargazing. Though the Milky Way remained lackluster all night, I got altogether respectable views of many deep-sky objects. I'm trying to get to the point where I can locate and recognize all of the Messier objects without charts, by memory, and 15×70 binoculars are perfect tool for this job. They're big enough to pick up almost all the Messier objects effortlessly, even in so-so conditions, and it's easy to scan the sky with them.

After sorting through the globulars in Ophiuchus — one of the few Messier groupings that I haven't fully mastered — I moved on to the summer Milky Way, and had a splendid time. I even picked up a fair number of 8th- and 9th-magnitude non-Messier star clusters by pure accident. (Remember, I was mostly working without charts.) No doubt about it, a so-so night in the country beats a superb night in the suburbs hands down.

In clear weather, the farthest hill (roughly 8 miles distant) is nearly as crisp as the trees in the foreground. Pollutants from power plants and vehicle exhaust are the primary cause of haze in the eastern U.S.

Tony Flanders

Still, I'm sure I would have enjoyed it much more if the transparency hadn't been so bad. The culprit for the bad conditions was obvious the next morning, as shown in the photo at right. By that time, the haze had thickened to the point where it was damaging views of hills just a few hundred yards away.

It's well established that most of the summer haze in my part of the world is caused by air pollution, primarily from power plants and vehicular exhaust. Nature plays it's role too. High humidity helps, though in fact it hadn't been humid at all that night. And forest fires, dust storms, and volcanoes can pump junk into the atmosphere much faster than humans can. But those phenomena are intermittent, while anthropogenic air pollution is ceaseless and relentless.

It's a bit of a paradox. I drive to dark locations to get away from light pollution, but in doing so, I'm contributing far more than my fair share to air pollution, which can be nearly as serious an obstacle. I still haven't really come to terms with that.


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Ben Waranowitz

July 18, 2007 at 11:56 pm

You are right, we pollute when we drive into the country. but ever look at all the people that attend NASCAR and the vehicles they drive? Not to start an indisciplinary war.. But you could carpool with another sky fanatic. I had a 1995 Dodge Neon with 5-speed and I coaxed 40 MPG on long trips at best and 36 at least. But I understand what driver practices use and waste fuel. Using brakes wastes fuel. Drive to use your brakes the least - is the simplest way to explain it. Of course I don't hesitate to use them for safety sake, but too many drivers go fast, then have to brake to wait for a light to change and traffic to get going at the next intersection. I simply coast, and often saved the gas others use to acceletate, then they have to brake.

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July 19, 2007 at 12:01 pm

Persistent Contrails are not contrails but an aerosol being deliberately sprayed into our atmosphere without or knowledge or consent. I've been watching the stars and airplanes since I was a kid and what we're seeing are not contrails. I see persistent trails when the humidity is high or low. I've seen a normal contrail in the same sky at or near the same altitude as these so-called persistent contrails. I see these trails stop and start in mid-sky as if the engine as stopped but the plane keeps flying. We our witnessing the geo-engineering of our atmosphere and planet. Don't you think that's causing so-called Global Warming?

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July 19, 2007 at 3:26 pm

I agree with the poster who said that it is aerosol spraying. Please Google or Yahoo some information about "chemtrails", which are believed by many to be being sprayed by the military for weather modification. A program developed by HAARP, but funded by the military. If you put in the keywords over at YouTube, you will find many documentaries on these subjects, as well. Chemtrails are known to linger a long time and then to spread into a thick white muck in the sky. I see them almost everyday, here in Connecticut. Yes, I agree, this is dangerous for the environment and for human health.

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July 20, 2007 at 6:19 am

I also agree with the poster who said it wa aerosol spraying. However although it is harmful to the enviorment and humans Chemtrails don't contrbute to global warming. In fact if anything aerosoles have the reverse affect of slightly cooling the earth since they reflected incoming sunlight. Jeremy

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Tony Flanders

July 20, 2007 at 10:06 am

I had no idea I was stepping into such a hornet's nest! When I mentioned persistent contrails, I was unaware that there's a whole subculture that's fascinated by the subject. It's not totally inconceivable that there's a conspiracy to spread sinister chemicals in the upper atmosphere, but I don't think the probabilty's high enough for me to invest any effort in studying the claims.

One thing I can say for sure, though: at least some persistent contrails are created by normal commercial jetliners. I've observed the entire process starting with the initial formation behind the jet's engines and wingtips to the contrail spreading to many degrees in width. Moreover, when one jetliner makes a persistent contrail, others nearby do so too. That's strong circumstantial evidence that the persistence is due to atmospheric conditions rather than the composition of the trails.

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Chris Weadick

July 22, 2007 at 5:27 am

Interesting to see this debate start up. I recall a Sunday shaping up to be a benchmark observing night. The sky was a beautiful dark blue mid day and not a cloud in sight.

As the airlines began their mid Sunday crossing of our sky I noticed that none of the contrails were dissipating. They would grow in girth but would not 'disappear'. By the time the sun was to set, the steady viewing had now become clouded by remanent jet contrails.

I had planned to initiate some research as to why some contrails dissipate and some linger other than wind currents and air pressures at different levels in our atmosphere.

Thanks for the "re-inspiration" to have another look.

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September 18, 2009 at 9:31 pm

"Others [terrorists] are engaging even in an eco-type of terrorism whereby they can alter the climate, set off earthquakes, volcanoes remotely through the use of electromagnetic waves... So there are plenty of ingenious minds out there that are at work finding ways in which they can wreak terror upon other nations...It's real, and that's the reason why we have to intensify our [counterterrorism] efforts."
Secretary of Defense William Cohen at an April 1997 counterterrorism conference sponsored by former Senator Sam Nunn.
Quoted from DoD News Briefing, Secretary of Defense William S. Cohen, Q&A at the Conference on Terrorism, Weapons of Mass Destruction, and U.S. Strategy, University of Georgia, Athens, Apr. 28, 1997.

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