Are contrails pollution?

When you look up and see the sky filled with white lines, you may get angry. you may wish they weren't there. You may even begin to think someone put them there on purpose. But, hopefully, you will find the right source for information, should you ever have that question.

But when looking into what those lines are, some seem to think they are filled with the chemicals that come out of the planes exhaust. In a very small way, that's true. The Visible part you see is a man made cirrus cloud. To understand that, and to fully understand what you see, you need to understand clouds.

Cirrus Clouds, thin and wispy. The most common form of high-level clouds are thin and often wispy cirrus clouds. Typically found at heights greater than 20,000 feet (6,000 meters), cirrus clouds are composed of ice crystals that originate from the freezing of supercooled water droplets. Cirrus generally occur in fair weather and point in the direction of air movement at their elevation.

link to source

Now, what is a contrail?

To answer this question, lets first identify what a contrail is. A contrail is the condensation trail that is left behind by a passing jet plane. Contrails form when hot humid air from jet exhaust mixes with environmental air of low vapor pressure and low temperature. Vapor pressure is just a fancy term for the amount of pressure that is exerted by water vapor itself (as opposed to atmospheric, or barometric, pressure which is due to the weight of the entire atmosphere above you). The mixing occurs directly behind the plane due to the turbulence generated by the engine. If condensation (conversion from a gas to a liquid) occurs, then a contrail becomes visible. Since air temperatures at these high atmospheric levels are very cold (generally colder than -40 F), only a small amount of liquid is necessary for condensation to occur. Water is a normal byproduct of combustion in engines.

www.wrh.noaa.gov...

So you can see that contrails are made of the same thing cirrus clouds are made of. The tiny particles needed for the nucleation process are called aerosols. What are they?

Aerosols are minute particles suspended in the atmosphere. When these particles are sufficiently large, we notice their presence as they scatter and absorb sunlight. Their scattering of sunlight can reduce visibility (haze) and redden sunrises and sunsets. Dispersion of volcanic aerosols The dispersal of volcanic aerosols has a drastic effect on Earth's atmosphere. Follow an eruption, large amounts of sulphur dioxide (SO2), hydrochloric acid (HCL) and ash are spewed into Earth's stratosphere. HCL, in most cases, condenses with water vapor and is rained out of the volcanic cloud formation. SO2 from the cloud is transformed into sulphuric acid, H2SO4. The sulphuric acid quickly condenses, producing aersol particles which linger in the atmosphere for long periods of time. The interaction of chemicals on the surface of aerosols, known as heterogeneous chemistry, and the tendency of aerosols to increase levels of chlorine gas react with nitrogen in the stratopshere, is a prime contributor to stratospheric ozone destruction. Credits: NASA Aerosols interact both directly and indirectly with the Earth's radiation budget and climate. As a direct effect, the aerosols scatter sunlight directly back into space. As an indirect effect, aerosols in the lower atmosphere can modify the size of cloud particles, changing how the clouds reflect and absorb sunlight, thereby affecting the Earth's energy budget. Aerosols also can act as sites for chemical reactions to take place (heterogeneous chemistry). The most significant of these reactions are those that lead to the destruction of stratospheric ozone. During winter in the polar regions, aerosols grow to form polar stratospheric clouds. The large surface areas of these cloud particles provide sites for chemical reactions to take place. These reactions lead to the formation of large amounts of reactive chlorine and, ultimately, to the destruction of ozone in the stratosphere. Evidence now exists that shows similar changes in stratospheric ozone concentrations occur after major volcanic eruptions, like Mt. Pinatubo in 1991, where tons of volcanic aerosols are blown into the atmosphere

www.nasa.gov...

Aerosols come from things like Desert dust, volcanic eruptions, and industry/pollution. When a plane flies, it uses internal combustion engines to do so. A by-product of that process is tiny particles that contribute to the aerosols that already exist (they are a very small portion of what's already there).

The white part that gets big and spreads out, is ice crystals. The pollution part is invisible. When you see a plane flying leaving no trail at all, it's still leaving the same stuff behind it as it does when the plane is making a trail. the important distinction is, what you see, as opposed to what you know is there. You can't see the pollution, you can only see the cloud made by the plane.

Visible pollution, reduction of sunlight, those are characteristics of contrails and clouds. You may not like clouds on a day at the beach, but I suppose that's why it's important to watch the weather before planning a trip.

Those who worry about contrails need to put more focus into the vehicles on the ground, in my opinion.

originally posted by: angryhulk
Those who worry about contrails need to put more focus into the vehicles on the ground, in my opinion.

I miss worrying about chemtrails.

The ability to research and understand combined with ATS membership has made the world a pretty dull place.

Technically they are not natural so they can be considered pollution. To say they are not is ignorant. Whether they are harmful pollution is the question. I would say that since we have so many jets flying around, they will have a negative effect.

Up till ten years ago CO2 was not even considered a pollutant but look now at what they are saying about it and that is because there is so much of the stored stuff being released at one time and less trees and specific plants to suck it up.

Twenty years ago if you would have said CO2 is a pollutant you would have been laughed at. It is because we are changing the concentration worldwide that it is causing problems. CO2 is a natural thing in the right concentrations. The wash water from cleaning chickens released in the water down river of a slaughtering house is natural but it is pollution since it is so concentrated. A natural thing concentrated too much is not natural.

originally posted by: rickymouse
Technically they are not natural so they can be considered pollution. To say they are not is ignorant.

I sure am glad I put this in the OP.

Visible pollution, reduction of sunlight, those are characteristics of contrails and clouds.

originally posted by: network dude

originally posted by: rickymouse
Technically they are not natural so they can be considered pollution. To say they are not is ignorant.

I sure am glad I put this in the OP.

Visible pollution, reduction of sunlight, those are characteristics of contrails and clouds.

They are geoeffective if they create clouds. So why do we have to prove they are when it is evident they are.

originally posted by: angryhulk
Those who worry about contrails need to put more focus into the vehicles on the ground, in my opinion.

Yes, that and industry.

originally posted by: rickymouse

originally posted by: network dude

originally posted by: rickymouse
Technically they are not natural so they can be considered pollution. To say they are not is ignorant.

I sure am glad I put this in the OP.

Visible pollution, reduction of sunlight, those are characteristics of contrails and clouds.

They are geoeffective if they create clouds. So why do we have to prove they are when it is evident they are.

What do you mean? there really isn't any "proving" to do, this is all well understood and undisputed.

the question that remains is do contrails have a net warming, or net cooling effect? That has been studied and likely will continue to be studied. I have seen it stated both ways, so I think the jury is still out on that part.

a reply to: network dude

According to an article I read from NASA, the effect of these Jets overall is warming. They do have some good scientists and good equipment over at NASA so I would tend to believe them on this issue. They have the ability to look directly at the evidence.

Now, I do not believe we need to colonize Mars just because I believe they make the right call on that issue of contrails and Jet exhaust.

a reply to: rickymouse

Initially, scientists thought that contrails, like the naturally occurring cirrus clouds they resemble and sometimes seed, had an overall warming effect. Although contrails clearly reflected incoming sunlight, they also trapped heat from below that would otherwise escape into space. Scientists therefore thought contrails had a net warming effect. Then Sept. 11, 2001 presented a unique opportunity to study what the sky looked like without airplanes and contrails. In the wake of the 9-11 terrorist attacks, the FAA prohibited commercial aviation over the United States for three days. That's when David Travis, an atmospheric scientist at the University of Wisconsin, Whitewater, thought to look at how temperatures might differ at temperature stations around the country. He found that [PDF], for those three days, the average range between highs and lows at more than 4,000 weather stations across the US was 1 degree C wider than normal. In other words, contrails seemed to raise nighttime temperatures and lower daytimes ones. But the real effect was in daytime highs, which were much higher. That would seem to indicate that, contrary to prevailing thinking, contrails might have a net cooling effect.

www.csmonitor.com...

I think it's still being looked at, but if you have a recent study, it may have been decided.

a reply to: network dude

Look at all the Jets in the air at a given moment and try to tell me that there is not some effect they have. They have the ability to initiate change and change causes altered weather patterns to occur. How much has not been evaluated. I am sure they aren't going to research this, people want to keep hopping around on jets going to places they would never drive to.

The overall effect of the airline industry is actually more travel occurring and a net increase on pollution. People would never have the time to go on cruises and go so far away. We got spoiled and net fossil fuels burned are going up even though efficiency is increasing.

a reply to: network dude

Visible pollution, reduction of sunlight, those are characteristics of contrails and clouds.

Classifying contrails with "clouds" is misleading. You don't burn jet fuel to get "clouds".

Unless you're trying to down play the environmental consequences of burning millions of tons of jet fuel in the atmosphere.

originally posted by: rickymouse
a reply to: network dude

Look at all the Jets in the air at a given moment and try to tell me that there is not some effect they have. They have the ability to initiate change and change causes altered weather patterns to occur. How much has not been evaluated. I am sure they aren't going to research this, people want to keep hopping around on jets going to places they would never drive to.

While I agree that people aren't going to give up air travel until a better alternative comes around, this is being studied as we speak. All aspects of this.
you just have to look a bit to see what's being discussed.

The overall effect of the airline industry is actually more travel occurring and a net increase on pollution. People would never have the time to go on cruises and go so far away. We got spoiled and net fossil fuels burned are going up even though efficiency is increasing.

With the new engines, more thrust per pound of burned fuel is what has been achieved. So bigger planes can take more people, farther, on the same fuel load. So things got a little better, but with air travel expected to double in the next 20 years, this will continue to be an issue.

I am not in any way saying planes don't cause pollution. In fact, I am saying exactly that. But the part of air travel that you see, (contrails) is not the pollution you are concerned with, it's a man made cirrus cloud. The pollution was there before the trail, during the trails, and after the trail. I would hate to be arguing the wrong point, and that is my only point in bringing this up. There have been a few here who don't seem to grasp this.

originally posted by: intrptr
a reply to: network dude

Visible pollution, reduction of sunlight, those are characteristics of contrails and clouds.

Classifying contrails with "clouds" is misleading. You don't burn jet fuel to get "clouds".

Unless you're trying to down play the environmental consequences of burning millions of tons of jet fuel in the atmosphere.

Not downplaying the pollution at all. Just trying to be sure that people aren't looking at contrails and thinking "they" are the exhaust of the plane. They are not, they are man made cirrus clouds as was described in the links in the OP.

While air travel is a small part of the big picture of the pollution issue we face, it's still an issue, and should be included when we talk about emissions from burning fossil fuels.

a reply to: network dude

The fact that this is not common knowledge concerns me.

a reply to: SlapMonkey

That's why I posted it. There seems to be some confusion about this and rather than proliferate the problem, I thought discussing the facts might help.

originally posted by: rickymouse
According to an article I read from NASA, the effect of these Jets overall is warming. They do have some good scientists and good equipment over at NASA so I would tend to believe them on this issue. They have the ability to look directly at the evidence.

They have been looking alright. They already measured a 2° lift in daytime temperatures when they got on the ball on 9/11 as the skies cleared, this was also noted by the FAA, and observed a net warming. Just that alone was enough to know how significant it is, and how more significant it will become in the future. The 9/11 no fly gave scientists their chance to get a baseline to work from, and even they were surprised by the result below;

"One study showed that contrails from just six aircraft expanded to shroud some 7,700 square miles,
One study looked at the aforementioned contrails that grew to cover 7,700 square miles. Those condensation trails arose in the wake of six military aircraft flying between Virginia and Pennsylvania on September 12, 2001. From those isolated contrails, unmixed as they were with the usual dozens of others, Patrick Minnis, a senior research scientist at NASA's Langely Research Center, and his colleagues were able to gain valuable insight into how a single contrail forms."

The University of Wisconsin-Whitewater are also conducting studies, and there are also studies into the actual pollution by aircraft.
Elsewhere, the UK government are reducing flying levels for jets in busy airlanes in the hope that it will reduce persistent contrailing and darkening and cooling of the skies.
Environmentalists have their own reasons for the need to maintain the natural temperature parameters for species where a prolonged difference might be critical for some species, and/or conversely where a specie should become dominant over another, so everybody has got their Nebs into this persistent contrail affair, and that also includes the pollution guys, they are casting a beady eye on the pollution in contrails with a mind to the future effects.
So, there is a lot going on when you look into it.

a reply to: smurfy

This may be of interest.

Here is a list of articles dealing with limiting contrail formation. something that is being looked into as well.
list

a reply to: rickymouse

A natural thing concentrated too much is not natural.

hussar - i KNEW i was right to dilute my water - dammed concentrated dihydrogen monoxide

Chemtrails exist. They are dumbing down America with this white fluffy clouds of chemicals. Don't even fill up a jug or bucket of rain water. That # has chemicals in it