How Aircraft Trails or Contrails are Effecting The Environment

Similar to the automobile exhaust fumes, the aircraft trails, known as contrails, are seen to be causing environmental warming and atmospheric pollution. As per a recent study, global air traffic is presently increasing almost by 3.5 percent per year. Many of these are long-haul extra flights that fly in high-altitude and form contrails. It is estimated that by 2050 these contrails will have greater impact on global warming by forming more CO₂ than aircraft engines.

First of all, contrails are observed to raise the atmospheric temperature. They spread themselves in high altitudes just like cirrus clouds and also moderate the atmospheric temperature. In a place where the mercury dips to a very low point, these trails can prevent the heat from the surface of the earth from escaping by trapping it. As a result, the night temperature is raised. During daytime it protects the earth from getting overheated by the rays of the sun by reflecting them back when they enter the atmosphere.

On the whole, the contrails are observed to have a warming effect on a place where they are seen to form frequently, though in places of temperature extremes they are seen to moderate the temperatures.

In the recent years, the marked increase in air traffic is looked upon as a matter of concern because environmental warming caused by contrails can contribute significantly to the environmental threat posed by global warming.

The fuel used in aircrafts is kerosene, which on being combusted emits carbon dioxide as an exhaust fuel. The carbon dioxide has a greenhouse effect on the earth. It allows the heat waves of short wavelength to pass through it and does not allow the heat rays of long wavelengths to pass through. As a result it traps the atmospheric heat energy causing the temperature to rise in the region. The fact that commercial aircrafts are producing about six hundred million tons of carbon dioxide per year is very alarming. Atmospheric carbon dioxide is one of the major contributory factors for global warming.

Emission of a large amount of carbon dioxide is due to incomplete combustion of fuel in the engine owing to low power. To enable complete combustion of the fuel the engine temperature should be raised. But with this, a new problem arises. High levels of nitrogen oxide are emitted into the atmosphere resulting in the formation of ozone. The presence of a certain amount of ozone is necessary in the atmosphere at high altitudes but in the lower levels it can prove to be a harmful pollutant. Studies conducted by research scientists show that from sixteen to thirty five percent of nitrogen oxide pollution is due to aircraft fuel exhaust gases.

Apart from carbon dioxide and nitrogen oxide the aircraft exhaust consists of steam particles that freeze due to extremely low temperatures in high altitudes into ice crystals. These crystals coalesce together into cirrus clouds. These cirrus clouds greatly contribute to global warming. Contrails are also known to cause global dimming by blocking the sunrays from reaching the surface of the earth. The aerosols present in the contrails are known to deflect the sunrays from their path preventing heat and light energy from entering the atmosphere of the earth.