Solar intensity in the Polar Regions is lower than in other parts of the Earth due to two main factors:

Regarding the difference in solar energy spectrum between the top of the Earth's atmosphere and the surface, the primary reason is the absorption of certain wavelengths by atmospheric gases. As mentioned earlier, gases like ozone (O3) and water vapor (H2O) selectively absorb specific wavelengths of light, particularly in the UV and infrared (IR) regions. This absorption alters the spectral distribution of sunlight, reducing the intensity of certain wavelengths while leaving others relatively unaffected.

For instance, ozone plays a crucial role in absorbing harmful UV radiation, protecting life on Earth from its damaging effects. Water vapor, on the other hand, absorbs a significant portion of IR radiation, contributing to the greenhouse effect and keeping the Earth's temperature warmer than it would be without an atmosphere.

In summary, the reduced solar intensity in Polar Regions and the altered solar energy spectrum at Earth's surface are both primarily caused by interactions between sunlight and the Earth's atmosphere. The angle of incidence and the presence of atmospheric gases significantly influence the distribution and intensity of solar radiation, shaping the unique environmental conditions of the Polar Regions.

Dr Murtadha Shukur thank you for your contribution to the discussion

The more slanted the sun's rays are, the longer they travel through the atmosphere, becoming more scattered and diffuse. Because the Earth is round, the frigid Polar Regions never get a high sun, and because of the tilted axis of rotation, these areas receive no sun at all during part of the year. Moving from the equator to the poles, sunlight hits Earth at a less direct angle, so the Sun's rays are more spread out and aren't as intense. Places near the poles are cooler than places near the equator because the sunlight they receive is more spread out and the surface doesn't warm up as much. At the poles, the ice, snow and cloud cover create a much higher albedo, and the poles reflect more and absorb less solar energy than the lower latitudes. Through all of these mechanisms, the poles absorb much less solar radiation than equatorial regions, which is why the poles are cold and the tropics are very warm. Both Polar Regions of the earth are cold, primarily because they receive far less solar radiation than the tropics and mid-latitudes do. At either pole the sun never rises more than 23.5 degrees above the horizon and both locations experience six months of continuous darkness. The spectral composition and amount of solar energy intercepted at Earth's ground and water surfaces are not exactly the same as that arriving at the outer atmospheric edges, because the atmosphere interacts with and modifies the radiation traveling through it. Energy that is absorbed by the Earth is not the same as the energy incident on the Earth's surface. On a perfectly clear or cloudless day, when the Sun is directly overhead, solar irradiation is still reduced due to absorption (16%) and reflection (6%) by particles in Earth's atmosphere. The Spherical Shape of the Earth. Because the Earth is a sphere, the surface gets much more intense sunlight (heat) at the equator than at the poles. During the equinox (the time of year when the amount of daylight and nighttime are approximately equal), the Sun passes directly overhead at noon on the equator.

Rk Naresh ... the sun is at a sufficiently large distance from the earth as to be safe to assume that the sun rays are not slanted, but nearly parallel to each other ... what is different for the sun rays is the distance they travel thru the atmosphere due to earth rotation, axis angle tilt, & the Milankovitch cycles ...

Fundamentally, it is due to the fact that much less solar energy reaches the Earth's surface in the Polar Regions than it does, as, in Central Europe or at the equator. The reasons for this are the low angle of incoming sunlight, the tilt of the Earth's axis and the orbit of our planet around the sun. Moving from the equator to the poles, sunlight hits Earth at a less direct angle, so the Sun's rays are more spread out and aren't as intense. Places near the poles are cooler than places near the equator because the sunlight they receive is more spread out (less concentrated), and the surface doesn't warm up as much. The more slanted the sun's rays are, the longer they travel through the atmosphere, becoming more scattered and diffuse. Because the Earth is round, the frigid Polar Regions never get a high sun, and because of the tilted axis of rotation, these areas receive no sun at all during part of the year. Near the equator, the Sun's rays strike the Earth most directly, while at the poles the rays strike at a steep angle. This means that less solar radiation is absorbed per square cm (or inch) of surface area at higher latitudes than at lower latitudes, and that the tropics are warmer than the poles. The angle of sunlight hitting the equator is more direct than it is at the poles, so the poles receive less direct sunlight.Because the Earth is a sphere, the surface gets much more intense sunlight (heat) at the equator than at the poles. During the equinox (the time of year when the amount of daylight and nighttime are approximately equal), the Sun passes directly overhead at noon on the equator. Both Polar Regions of the earth are cold, primarily because they receive far less solar radiation than the tropics and mid-latitudes do. At either pole the sun never rises more than 23.5 degrees above the horizon and both locations experience six months of continuous darkness. At the same time, the sun's rays strike the earth at the poles at a very oblique angle, resulting in a much lower concentration of heat and much less radiation so that there is, in fact, very little heating of the atmosphere over the poles and consequently very cold temperatures. The Sun's rays strike the surface at different angles, depending on the latitude. The higher the latitude, the smaller the angle of incidence, thus the less solar insolation reaches the surface. This is one of the reasons why the equator is warmer than the poles. The spectral composition and amount of solar energy intercepted at Earth's ground and water surfaces are not exactly the same as that arriving at the outer atmospheric edges, because the atmosphere interacts with and modifies the radiation traveling through it. Solar radiation spectrum at sea level has pronounced dips, which are due to absorption in the atmosphere. Figure 1 shows this spectrum, as compared to the incident spectrum on top of the atmosphere. These dips are also not present in the reflected radiation from the earth atmosphere: the albedo. Most of the Sun's energy reaching Earth includes visible light and infrared radiation but some is in the form of plasma and solar wind particles. Other forms of radiation from the Sun can reach Earth as part of the solar wind, but in smaller quantities and with longer travel times.