Looking at the sky, we were surprised by two white lines trailing behind the plane in childhood. The reasons why a plane usually leaves a white streak are much simpler than it might seem.
In this short article, we will clearly analyze why these traces come from private jets or other aircraft. We’ll explain the example in detail with a fun little experiment that you can reproduce yourself at home! You will also find out why trails remain from some planes but others do not produce them. Moreover, we will find out whether they are harmful to people and the environment.
Why do jets leave a white trail in the sky?
In order to understand the formation of white stripes from airplanes and helicopters, you can conduct a simple experiment:
- Take a bottle on a hot day
- Pour water into it
- Put it in the refrigerator for several hours.
If you pull out the bottle after the allotted time and put it on the table, you will soon notice how the plastic surface fogs up and water droplets form on the bottle.
What is this? It’s condensation!
It appears due to the temperature difference – a cold bottle in a warm room will always cause such an effect. The same thing happens if you walk through the cold wearing glasses and then enter a warm room. Glasses will fog up immediately.
How is the condensation related to the white plane trail?
It turns out directly. The white trail from airplanes and helicopters is called a contrail. At their core, these bands are clouds. Only it is not nature that creates them, but the aircraft engine. The main reason for the appearance of a condensation trail is moist air and low temperature overboard. When fuel, kerosene, burns in the aircraft engine, hot jets of gas and steam are thrown overboard. And since during the flight at high altitude, the temperature is about minus 40 degrees, this steam becomes condensate, turning into fog or small, small ice crystals.
Crystals evaporate more slowly than ordinary water. For this reason, the white jet trail remains in the sky for a very long time. At the same time, the higher the humidity of the climate and the colder it is overboard, the longer, thicker, and brighter the white stripes are.
Why are some planes not have a white trail?
Sometimes you can notice that a plane or helicopter flies high but does not leave white marks behind. With what it can be connected? It turns out that this phenomenon also has two reasonable explanations:
- First of all, the presence of a condensation trail depends on the humidity of the air. Humid air is the air that contains many, many small particles of water. Accordingly, at a high sub-zero temperature, they freeze if they are doused with hot steam from burnt fuel. If the plane flies over a region with dry air which means that there are practically no small particles of water in the air, then there is nothing to freeze overboard. The contrail from an aircraft in such areas may not appear at all, or it will be pale and quickly dissipate.
- Also, as a rule, a contrail stream does not form in airplane jets and helicopters that fly low. This is because the air temperature overboard is not low enough, and the water particles simply do not have time to turn into crystals.
White footprint and environment
If the white plane trails in the sky are clouds formed from condensation, are they harmful to the environment? In fact, scientists still do not have a clear answer to this question.
There is an opinion that plane smoke trails, which streak the entire atmosphere, prevent harmful ultraviolet radiation from the sun from penetrating the earth. And this means that the risk of accelerating global warming and general climate change on the planet is several times reduced.
Some groups of researchers are urging pilots to abandon direct routes and build their flights by taking into account the humidity. According to their plan, the aircraft should move, avoiding certain areas in the airspace. But such a decision will inevitably lead to an increase in fuel consumption and an increased emission of harmful substances from its processing into the air.
Chemtrails – fact or fiction?
According to conspiracy theorists, sometimes the government sprays some dangerous “chemicals” under the guise of a contrail from airplanes. They are called “chemtrails” or “chemtrails”. This is a fairly common conspiracy theory: for example, there are 56 chemtrail groups on VKontakte, some of which have thousands of members. There are more than 5,000 posts on the hashtag “chemtrails” on Instagram.
Supporters of this theory believe that not every jet cloud from an aircraft is a chemtrail – such trails remain in the sky for several hours and expand over time. The theory’s origins go back to Operation Popeye by the US Army during the Vietnam War from 1967 to 1972. Then aviation sprayed silver iodide in rain clouds to cause rain, thereby depriving the enemy of the crop and washing out roads.
However, in 1977 the UN adopted the Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques. Therefore, in fact, such trails do not spray any chemicals.
FAQ
What kind of plane leaves a trail?
You can see airplane vapor trails in the sky more often after aircraft fly at an altitude of at least 8000 m. In other cases, such white stripes are considered rare.
How long do contrails last?
On a hot summer day, the contrail hangs in the air for about two minutes. In warm air, this fog disappears faster. And in winter, white marks last longer.
What are plane trails made of?
Plane trails are visible condensation in the air. It consists of condensed moisture – drops or ice crystals.
Can you see contrails at night?
Yes, you can really see the contrails at night. The ice crystals that are considered jet vapor trails can easily reflect light from outside.