Have you ever stood outside on a sunny day looking up at a bright blue sky and seen long white lines everywhere? They cross like a web in the horizon. What are these lines called? Well, let’s talk about them – they are contrails which are quite Vanish in most skylines nowadays. But are they purely decorative, or do they have some significance, why should we be concerned with them? What impacts do these contrails have on our environment? Let’s find out.
What are the Contrails and what causes them?
As much as popular culture wants to argue, contrails do not only refer to airplanes’ exhaust. They are rather manmade clouds consisting of water vapor and soot, both by products from burning aircraft engines. As Stephen Barrett, an engineering professor with ongoing research at the University of Cambridge said “A contrail is an artificial cloud. They are very much the same as natural cirrus clouds, except they start as long and linear.”
There are particular conditions in the atmosphere required for a contrail to be formed. The “ice-super saturated” air also has to be high in moisture content for the water vapor no to evaporate and cool enough for the vapor to freeze. Such prevailing atmospheric conditions are mostly present at show cruising altitude levels of approximately 35000 feet above sea level, though this happens only about 5-10% of the time.
The persistence of contrails is also dependent on the atmospheric conditions. In warmer dry air, they will only last for a few seconds or minutes. But under the right combination of cold and humid weather, contrail clouds can last as long as six hours and spread-out all over the sky.
The Unexpected Role That Contrails Play In Contributing To Climate Change
Even though most people think contrails are harmless, recent studies show that they pose a considerable warming potential to the Earth. Contrails have, and it is surprising to note, a thermal effect equal to the totality of all greenhouse gas emission by aviation in CO borrowing. The main distinction is the time frame: carbon emissions increase year in year out and it takes decades before they peak but in the case of contrails, they have an upfront impact but only for a short duration.
According to Marc Stettler, a transport and environment professor at Imperial College London, every year, contrails are responsible for approximately 2% of anthropogenic warming. This sounds negligible, but considering the fact that the future forecast of commercial air traffic is rather bright, such cumulative warming may turn out to be alarming.
The mechanisms by which contrails affect climate include a whole range of effects. They do reflect sunlight, similar to other clouds, and therefore have a cooling influence upon Earth. On the other hand, they insulate up radiated energy from the earth’s surface. More often than not the warming effect is greater than the cooling effect, which is more relevant at night when there is no sunlight to reflect.
Potential Solutions and Future Impediments
The consolation is that there are prospects for constraining the warming impact of contrails. One interesting strategy tries to correct flight trajectories concerning the formation of contrails by activating flight avoidance over ice supersaturated environments. Most times a small altitude change of around one thousand feet would sensibly suffice a lot.
Such a move however presents another set of hurdles. For now, atmospheric forecasting does not possess the required level of precision at altitudes where aircraft usually cruise. Such studies are being conducted enhancing these predictions and making more relevant flight planning tools.
How beeing back looking for trial bores companies like Google and several airlines have already been engaged in small-scale trials. The next step, however, seems especially appealing in terms of googles over scottish airspace or a large scale in the atlantic flight disbelief: Barrett said it will begin to test such strategies across more extensive areas.
It needs to be mentioned that it is only part of the problem, and in fact, a small part of the problem, to deal with the contrail issue. Stettler further states that countering the contrail effects should not substitute the attempts to reduce the aviation CO2 emissions. The aviation industry has to address both problems in order to reduce its overall ecological footprint.
Ever deepening our understanding of the atmosphere and the ways human beings are changing it, we are reminded of the simple yet effective contrail – the links between the man and the climate. We will be able to tackle the issues of air transportation more consciously, imagining a different world by realizing these links.
