In optics, what effect does increased temperature typically have on the refractive index of air?

In optics, temperature has a notable impact on the refractive index of air. As temperature increases, the density of air decreases because the air molecules move more rapidly and spread apart. This reduction in density typically leads to a decrease in the refractive index. The refractive index is the ratio of the speed of light in vacuum to the speed of light in a medium. When the medium (in this case, air) becomes less dense due to higher temperatures, light can travel through it more easily, which results in a lower refractive index.

It’s important to understand that while various factors can influence the refractive index, such as humidity and atmospheric pressure, the direct effect of increased temperature on air specifically results in a decrease in the refractive index.