Sky and Weather Photography by Michiel de Boer
	the contrail problem   view the contrail gallery   A few streaks in the sky are not a problem. But what most people do not see, is that the sky often is fully covered with contrails. And in the worst case there is a real cloud deck created by contrails (contrail cirrus). To know if a thin, high cloud deck (cirrus) is created by airplanes you need to observe the sky during it's development. The problem is that there are cloud decks in the sky that do not belong there. Contrail clouds keep more heat than they reflect back into space, and thereby will contribute seriously in global warming, especially in the future, because the air traffic is increasing all the time. And there will presumably be other influences as well. Beside this main problem, they are annoying as well... They turn a sunny day into a day with a weak sun more often than you might think. And personally I do not like the sight of them either, although I must admit that they can sometimes be interesting.   how do they exist ? Cold air, cannot hold as much water vapor as warm air. If the humidity is too high, the water vapor starts to condense. Fog is the result. A process of burning produces a lot of water vapor. But the air does not condense because it is too hot, and by the time is has cooled down, the water vapor has spread out too much. About 8 to 12 kilometers up in the sky where the airplanes fly, the air is extremely cold. At this height, the hot exhaust of the airplane's engines cools down in a matter of seconds. The water vapor gets no chance to spread out while cooling down, and thereby immediately starts to condense. This is the condense trail behind the airplane. At a certain point - a combination of the temperature and the humidity - the contrail does not vanish, but remains and grows instead: A persistent contrail. More water starts to condense, also on the soot and other exhaust particles. Depending on the winds, it can grow into an extremely wide tail or shape, which looks like a normal cloud. When there are several contrails behaving that way (which is commonly the case), an unnatural cirrus cloud deck is born.   can we stop it ? The only actual way to stop contrails is to let all airplanes fly lower. At lower heights, there will be no condensation, no contrails. But this gives other problems: At lower heights the air is more concentrated, causing more friction of the air. And more friction means there's more energy needed, which means again more fuel is needed, resulting in more pollution... Also, there will be more noise from the airplanes because they're closer to the ground. Both these new problems can be best solved by simply flying a little slower. Just like a car, an airplane pollutes more and makes more noise at high speeds. Also, new airplanes could be built to be more fuel efficient for lower altitudes. And a very nice option would of course be to not travel so much, but you and I know this will never happen. Air traffic will only increase.   other questions Is there more information ? Yes, visit Contrail Education or contrails.nl. What are chemtrails, do they exist ? When I started this site in 2003, I named it 'Chemical skies', just because I liked it and it referred to the contrails. I did not know about chemtrails, I just thought it was another name for contrails. When Robert VanWaning from contrails.nl wrote that chemtrails was something else I did a little research. There are many confusions and many theories about the 'chemical trails'. There are people who believe that the government(s) are spraying chemical stuff to make us ill. There are people who believe that the planes spray pieces of metal to reflect heat back into space and prevent global warming by doing this. And there are many other theories. Some of them are quite realistic. Someone wrote me there are presidential candidates against chemtrails. I do not believe in chemtrails, it's too laborious. There are much more advanced and invisible ways to do certain things, if anybody really wanted to... Is this airplane spraying something ? The photo on the right here is a typical example of what looks like a 'spraying' airplane. It is a rare air-pressure contrail, it exists in unusual high humidity. This same effect can sometimes also be seen on very fast driving race cars (Like Formula 1 or Indy car). But high in the sky it doesn't disappear because it freezes immediately. Why do you worry about contrails, there are many other forms of pollution! Most kinds of pollution are well known. But I find it remarkable that nobody even seems to really see those streaky skies. I want to make attention to this phenomena. Let us realize this is also serious pollution, and can also become very threatening in the future when the aviation increases. And thereby, i get confronted with it everyday as a 'sky photographer'. Written on October 12, 2005. Last edited: January 3, 2006