PHY WAVE

The penetration of electromagnetic wave (EM wave) depends on its degree of absorption in the mdeium in which it passes through. Wabes that are readily absorbed by the medium cannot pentrate deep into it, whereas waves that are not absorbed by the medium can penetrate through it without much attenuation.

A good example is that visible light from the sun can reach the earth surface only with little to moderate absorption in the atmosphere. But ultra-violet light of high frequency (short wavelength), especially UV-C, is readily absorbed in the upper atmosphere by the ozone layer. This makes UV-C less penetrating in the atmosphere than visible light.

Likewaise, infrared from the sun, especially the near-infrared, can penetrate the atmosphere, but the longer wavelength far-infrared cannot. All these phenomena are due to the different degrees of absorption of different media to different frequencies of EM waves.