Sky Has No Limits...! So Do I....!

On seeing the picture displayed beside, you may understand what the article is about..? Yes, you are correct.. you must have observed on the sky an aircraft leaving white streaks behind it..! can you guess what it must be?
Do they spray some chemicals to produce artificial rain?
No. They are called as "CONTRAILS" a short form for "Condensation Trails". Some may call it as "vapor Trails" too.

But how do they form?
We all know that the atmosphere at 30,000 feet above sea level is of very low pressure and the temperature goes in minus, which is literally freezing cold. The availability of air is also very less which can be found only in traces.
The Contrails may happen when the engine exhaust gas gets cooled down suddenly by the surrounding cold air, it precipitates a cloud of water droplets. If the air is too cold, this water droplets may form tiny ice crystals.
But the "Contrail" must not be mixed up with the "Wing tip Vortices"..!

Wondering what is a "wing tip vortex?"

Imagine a calm river with out any disturbance on the surface of water. If we sail through a small boat, it creates its own wake which can be seen behind the boat. In the picture shown beside, we can see the wake created by a boat. Similarly, now when we compare a plane wing's tip, it creates a turbulence in the stream of undisturbed layer of air in the atmosphere. This turbulence is created due to mass of spinning air, whose center is at lower pressure. The wing tip vortices are different from the Contrails. The wing tip vortices create a turbulence of spinning air, whose centre is at low pressure condensing the water vapour, thus forming a streak around the wings.






Now lets see the difference between the Wing Tip Vortices & Contrails...!

Wing Tip Vortices:

1. Seen only during low altitudes.
2. Seen mostly during take-off & Landing.
3. Seen when the aircrast travels at lesser speed.

Contrails:

1. Seen at higher speeds.
2. Seen at higher velocity.
3. Seen behind the engines.
4. Originates from the exhaust of the engines.

So whenever we see something like a cloud behind an aircraft, we can identify between a Contrail & a Wing tip Vortex.