More Optics

[ms. confused]

Why does dry asphalt appear to be wet on a hot, sunny day?

[daster]

The hot asphalt warms the air around it, so when light strikes it, it's refracted upwards. (Hot air is less dense than cold air.) The refracted ray then meets your eye appearing to be shining/glowing from the asphalt instead of the sun/sky, a wet mirage develops which actually looks like the sky.

[prasanna]

Check out this link on mirage!
http://www.suite101.com/article.cfm/science_sky/78177