Sunlight striking a blacktop highway changes primarily into heat.

Here's why:

* Black asphalt absorbs almost all wavelengths of light. This means that the energy from the sun's light is not reflected back, but is instead absorbed by the asphalt.

* Absorbed light energy is converted into heat. This is why blacktop highways get so hot in the sun.

While a very small amount of the light might be reflected, the vast majority is converted into heat.