The Astounding Effects of Contrails on Climate

So, we hear a lot about they "mythical" chemtrail, but what many of us dont know is that contrails can have an adverse affect on climate themselves. The main product of contrails are water and dust, both found from the jet engine exhaust.

Contrails form when hot exhaust gases are expelled into a super cooled environment, mixing with surrounding air. Under suich conditions the water vapour rapidly condenses into water, then ice crystals. This happens in a fraction of a second, and is the reason contrails form a few feet the exhaust rather than straight from it.

The concern with contrails is when they linger. Like natural clouds, the water vapour, or ice crystals feed off water already present in the atmosphere, creating a chain reaction which can often create a sheet of cloud (which by this time is called cirrus). This can occur for hours, or until the loud reaches a scetion of dryer air.

Now that we know that the main product is ice, lets examine the reflectivity of ice crystals in the atmosphere.

Its is a well known fact that fresh snow has the highest albedo of most of the kind ofs surfaces within the troposphere, at about 70 to 80%. Surface Ice reflects approximately 30 to 40% of sunlight, while the ice found in cirroform clouds (include contrails, cirrus, cirrostratus, cirrocumulus, and cirrus derived from contrails), reflects about 50 to 60% of sunlight, and sometimes up to 70%



Now considering the amount of air traffic over Europe and North America, imagine the amount of sunlight being reflected back out into space. It would be an enormous amount.

Cirrus clouds also trap heat within the earth during the night. When cirrus is present, or even on a cloudy night...the temperature will not drop very much. The difference between the maximum temperature and the minimum temperature is known as, the diurnal temperature variation. On cloudy days, the diurnal temperature variation is very small. That means that the difference between the maximum and ther minimum temperatures will be very little. On clear nights, the diurnal temperature variation is usually larger, as the long wave radiation brought in is not trapped by cloud cover, meaning the earth cools quicker.

One major event, proved that contrails have quite an effect on diurnal temperatures, and climate. That was September 11th, 2001. Below are comparisons of the north east USA before the terrorist attacks and after, when all air traffic but airforce one and its escorts were grounded.

BEFORE



AFTER



Now while they are alightly different images, it should be apparent that contrails are having a great affect on the diurnal temperature variations in the United States. On the three days preceding 9/11, the diurnal temperature variations across 48 of the stated in the US, had become 2 degrees more than usual!!!!!



So, with this in mind, and the ever increasing reliance on air travel, its easier to imagine that the effects of contrails will always have an effect on our surrounding environment.


I wasnt going to add this but I thought I would give the chemtrail believers a chance to disprove this theory as its only fair.

Apart from this, what is everyones else opinion? Should we be searching for alternative measures to stop contrails from affecting our climate, or is this an over exagerating of a seemingly innocent problem?

References:
www.pbs.org...
www.fas.org...
en.wikipedia.org...
jetcloud.blogspot.com...

Excellent post Oz and a subject that as you know I'm quite interested in.

For a long while it was thought that the net effect of contrails was cooling - they do indeed reflect back incoming radiation during the day (they increase Earth's albedo).

See, for example, Airbourne observations of contrail effects on the radiation budget - Peter Kuhn, 1970

Pat Minnis etal published a much quoted paper Contrails, Cirrus Trends and Climate in 2003 in which it was concluded:



It should be noted though that some more recent studies have called into question the effect on diurnal temperature range noted in the post 911 studies. For example, Contrails, natural clouds and diurnal temperature range - Dietmuller etal 2007

Research into this continues, but the current consensus is that persistent contrails produce an overall net increase in temperature due to the reflection back of outgoing radiation at night and in winter. This effect is most noticeabe at higher latitudes and it may be one reason why Arctic regions are warming greater than other parts of the planet - a lot of tranatlantic flights cross Greenland, for example.

The IPCC 4AR only briefly touches on this issue and highlights the current uncertainties, but indicates that this is a likely radiative forcing (warming) of at least +0.010 W m–2 as a result of aircraft contrails.

Doesn't sound a lot, but it well may be higher and will of course be greater in areas of heavy aircraft traffic - such as Europe and N America.

There is also the simple fact that increased air traffic means more contrails meaning that on some days when, without air traffic, we'd have clear blue skies, we instead have an in increasing pall of high cirrus cloud. This was very noticeable in the Scottish Highlands on the 17th October this year when there was not a natural cloud in the sky, yet by midday it was looking like this:



[edit on 25-10-2009 by Essan]

That would certainly explain the continuation of the glacial melting, yet the decrease in global avergae temperatures over the whole planet.

Im wondering if they determine cooling by measuring maximum or minimum temps?

Bravo, Oz, I for one am glad to see sanity and reasoning still have a place here on ATS.

Those satellite "before" and "after" views certainly drive home just how much air traffic, and their residual contrail/cirrus cloud formation, has increased in the last couple decades.

Thanks

It certainly is an issue which has not been fully dealt with yet. Its only since 9/11 that we have started to understand how much of an impact contrails actually do have on climate.

Its certainly going to be interesting in 20 years time when air travel will have increased on an exponential scale. We may even start seeing this effect over Australia, South Africa and South East Asia, as contrails keep heat out the upper troposphere's in these locations

I've wondered about the effects for years, but not so much about the visible part. What I wonder about is the effect of taking subzero temperature air in at one end and spitting it out around 600 degrees Centigrade at the rate of 200-2800 lbs per second at the other. Think of all the engines in use at any given time: the total must be enormous.

While it is true the cubic volume of the atmosphere is immense, the cumulative effect of thousands of jet engines continuously heating the same belt of atmosphere for decades simply has to have an effect, don't you think?

reply to post by apacheman

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Sorry

Im not sure what you are exactly saying here. Are you insinuating that hot exhaust warms up the environment?

Thanks for this VERY good thread, Oz! This is important stuff!

When I read your OP i thought about this animation of civil air traffic worldwide in 24 hours.... And this goes on every day on our vulnerable mother Earth.

This can't be good...

YouTube Link

The amount of air traffic that goes overhead is just obscene. People don't realize how crowded the skies are. There are 5,000 flights in the air at any time over the US.

I figured you were gonna say that all the particles were going to affect weather.

reply to post by nixie_nox

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They do

What particles are you refering to by the way...the dust of the water vapour, or neither?

reply to post by OzWeatherman

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both reilly. Dust particles are known to stir up rain where it shouldn't. People always say that it seems to rain more on the weekends. But that is an actual observation. All the particles emitted from exhaust from traffic builds up and creates rain on the weekends. It never occurred to me that planes could cause the same effect. And the water has to change humidity as well.

reply to post by nixie_nox

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That is true. Dust actually attracts water molecules, acting as mechanism by which they can increase droplet or water molecule size, creating cloud and occasionally rain.

By the way, water already present in the atmosphere is humidity, it doesnt need to change its form

reply to post by OzWeatherman

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What I meant more was that by crop dusting humidity and basically redistributing it, has to have some effect

Your taking water and putting it in places it shouldn't be, and basically spreading it evenly over the US. or anywhere else for that matter. I just pick the US because I do know they tend to have a lot more air traffic.

reply to post by nixie_nox

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Well you arent really redistributing it.....but you are certainly altering the quantities of water. By adding water you are also increasing the likelyhood of attraticn more water though

Just a idea you may want research. I wonder if a reduction in night terrestrial cooling causes an increase/decrease in the duration/intensity of radiation fog? such as a fog event instead of a frost event. Or the other way cloud cover reduces cooling, reducing fog

btw...S+F

So your argument is that BECAUSE contrails have such a great affect upon the climate in terms of providing an increase in overall clouds... that a Chemtrail operation could not exist?
It is, as you said: "MYTHICAL?"



I AGREE with you that the massive amounts of artificial clouds put into the sky by normal air traffic has an affect upon the climate. Logic and science has shown this.

But this does not at all disprove the existence of a Chemtrail program.

If the purpose of Chemtrails is to increase clouds in an attempt to increase the amount of sunlight and heat which is blocked, then: using data based on such things like volcanic eruptions, AND YOUR OWN INFO ON THIS PAGE: such as the affect of airplane contrails on the climate, it would seem LOGICAL for scientists to try to MIMIC this behavior in their attempt to slow/stop global warming.

What I am trying to say is that if Global Warming IS happening to a degree where action MUST be taken.... and the normal aircraft contrails clearly are helping but not enough. It would be logical for scientists to try to find ways to increase what is already happening: normal contrails. By improving and refining the cloud which an aircraft puts out... to be MORE stable and long-lasting then a regular aircraft contrail.

If the purpose of Chemtrails is something other than to control global warming, such as HAARP, then it would cease to have any relevance or attachment to the fact that normal contrails have an affect on the climate.

[edit on (10/27/09) by AllSeeingI]

reply to post by AllSeeingI

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If you re-read my earlier post, you'll see that the current consensus of opinion amongst atmospheric scientists studying them is that contrails cause warming.

See also: www.co2offsetresearch.org...

reply to post by AllSeeingI

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But they dont need to increase the time contrails last as they do that themselves. When the temperature and humidity is correct this will always occur.

Nice post as always OZ.
Now the funny part is that I hear there’s a fuel additive, used by the Air Force, which can suppress contrails. It’s used on aircraft such as the Stealth Bomber, so it does not have a big white arrow pointing out its location in the sky. There is some reason why they don’t use it on all aircraft, so I am guessing that it must be either hazardous, expensive, or highly classified. I get a kick thinking back on all the years we have spent explaining to people that there are no additives to make contrail/chemtrails, when folks should have been more worried about the chemicals in the exhaust of planes that don’t have a contrail…

As I understand your thread suggests that the increased amount of contrails has a WARMING affect on the planet because of the clouds which linger and TRAP heat at night. During the DAY however clouds reflect heat and reduce temperatures.

This would explain the logic behind the EXACT reason why the CHEMTRAIL flights are MADE to expose themselves during daylight and risk being seen and exposed (AS THEY ARE EXPOSED MORE AND MORE DAILY). They are forced to spray during the day because this is the only time they can have an affect on the cooling of the planet. As you said.... night clouds increase temps and decrease the diurnal temp range. Which I agree is proven science.

If I was a scientist who was convinced that global warming was an issue... AND saw the data such as you presented in this thread and data from volcanic explosions which show that clouds decrease the global temps by blocking sunlight and radiation, wouldnt it be LOGICAL to attempt to artificially mimic this 'natural sunshade' during daylight hours.




Given the necessary conditions. YES!

But if conditions are not perfect for it.... It may require a special sort of contrail mixture to achieve the goal of blocking enough sunlight to reduce global warming.

[edit on (10/28/09) by AllSeeingI]