Why does the air temperature drop with altitude?

The air has a transparent structure, and therefore is not susceptible to the heat of the sun’s rays and does not heat up from them. But the Earth is exposed to the thermal effect of the Sun, warms up from it. The atmosphere is heated by the heat given off by the Earth. Accordingly, the closer to the surface, the warmer the air, and vice versa, the farther from the Earth, the cooler the air. With each kilometer, moving away from the surface of the Earth, we can observe a decrease in air temperature by about six degrees.