Question

The heat of the _________________________________dries up the puddle

Answer 1

This is a very good, perceptive question! Yes, of course the optical artifacts that look like puddles on the road are due to variations in the refractive index of the air. Some bits of air (like that near the surface of a road) have different temperatures from other parts of the air and the air acts a bit like a lens, bending light from its straight path. The "puddles" are called mirages. 

Of course the heating is often due to the sun (it can be due to other things like the burning of fuel). Sunlight refracts in the atmosphere just like light from any other source, and so the sunlight has two roles -- one of which is to heat surfaces and also the air, and the other is being bent by the differentially heated air to arrive in various places with various strengths.