What is that watery reflection in the road a few yards in front of your car..then when you get closer it...?

Question

disappears?

as you are driving on flat road...it looks like big puddles of water in the road but they disappear as you get closer. what is that and how come you can never actually drive through them?

Answer 1

its a mirage.

Answer 2

It is a mirage.  A mirage is a naturally-occurring optical phenomenon, in which light rays are bent to produce a displaced image of distant objects or the sky. The word comes to English via the French mirage, from the Latin mirare, meaning 'to appear, to seem'. This is the same root as for mirror. Like a mirror, a mirage shows images of things which are elsewhere. The principal physical cause of a mirage, however, is refraction rather than reflection. A mirage is not an optical illusion. It is a real phenomenon, and one can take photographs of it. The interpretation of the image, however, is up to the fantasy of the human mind.

Highway mirage

A highway mirage (asphalt mirage, hot-road mirage or road mirage) is an inferior mirage seen on roadways almost every day and night. Of course hot-road mirage is much more prominent on the hot sunny days. Warm air is less dense than cool air, and the variation between the hot air at the surface of the road, and the denser cool air above it creates a gradient in the refractive index of the air. Light from the sky at a shallow angle to the road is refracted (bent) by the index gradient, making it appear as if the sky were reflected by the road's surface. The result looks like a pool of water on the road, since water also reflects the sky.

Answer 3

Ever heard of a mirage? Anyway, it has to do with light reflecting off the ground, or something like that... or light reflecting off the sky, one of the two, I think. Either way... no, it's not really a puddle, it's an illusion.

Answer 4

That's called a mirage.

As the road gets hot it warms the air above it.  The warmed air becomes turbulent, which causes variations in density.  Light passing through this turbulent air gets bent more or less depending on the density of the air.  Because of this bending of light, it appears as if the road is actually REFLECTING light (rather than the air above it REFRACTING light).  Hence, it appears that a puddle is in the road.

As you get closer the air is still turbulent, but the angles don't line up properly anymore to create the "reflection" illusion.  That's why the "puddle" always seems to recede.

I hope that helps.  Good luck!

Answer 5

It's a hot road mirage. There's a photo and explanation at http://en.wikipedia.org/wiki/Mirage

Answer 6

It's a mirage (not a thermal), and is a form of optical illusion.  The hot air layer above the pavement refracts skylight; the result has the appearance of water (which reflects skylight).

Answer 7

It's called a"Thermal"

http://en.wikipedia.org/wiki/Thermal

Answer 8

It's due to refraction (bending) of light near the hot surface of the road.   It's the sky.