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Wednesday, November 10, 2010

Jet contrails from some angles look like missile trails « Contrail Science Overflow

November 9, 2010 / Uncinus

Jet contrails from some angles look like missile trails

[Edit - This post was originally from Jan 19th, 2010.  I've updated it with information about the "Mystery Missile" contrail of Nov 8, 2010, at the bottom of this post.  Clearly it's the same thing]

An interesting contrail cropped up off the coast of San Clemente, Orange County, California on December 31st 2009. The curious shape led some people to think it’s a missile launch, which it does kind of look like (all taken from San Clemente)

"Missile-like" contrail. Note this is the Dec 31st contrail, not the Nov 8th CBS one. That's at the bottom of the post.

Click these for larger images:

The idea that it’s a missile launch comes from three misconceptions. Firstly that the trail is vertical – it’s not, it’s a horizontal trail, at around 32,000 feet (about six miles). It’s the same as this:

This contrail is no more vertical than the road is, and nor are the power lines at 45 degrees. Everything is horizontal – it’s the just the angle you are viewing it from. All of these show horizontal contrails.

Secondly there’s the misconception of direction, that it’s flying away from the viewer, when it’s actually flying towards the viewer. This is because the “base” of the contrail seems wider than the tip. Perspective tells the brain that this mean the base is closer. But actually you can see the base has been greatly spread by the wind. Since it’s so far away the effects of perspective are greatly diminished, meaning the actual width of the contrail is what is creating the illusion. Imagine if a plane with a 100 mile long spreading contrail were coming towards you; what would it look like? It would look exactly like this.

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