Why is incoming solar radiation not absorbed and why heating by solar radiation is smaller at high latitudes compared to low latitudes?
There are two main reasons why incoming solar radiation is not absorbed and why heating by solar radiation is smaller at high latitudes compared to low latitudes:
1. Angle of incidence: The angle at which sunlight strikes the Earth's surface affects the amount of solar radiation that is absorbed. At high latitudes, the sunlight strikes the Earth at a steeper angle compared to low latitudes. This means that the sunlight is spread out over a larger surface area, which reduces the amount of solar radiation that is absorbed per square meter.
2. Atmospheric scattering: As sunlight travels through the Earth's atmosphere, it is scattered by molecules in the air. This scattering reduces the intensity of the sunlight that reaches the Earth's surface. At high latitudes, the sunlight has to travel through a thicker layer of atmosphere than at low latitudes, which means that more of the sunlight is scattered away.
As a result of these two factors, the amount of solar radiation that is absorbed by the Earth's surface decreases with increasing latitude. This is why the average temperature of the Earth's surface is colder at high latitudes than at low latitudes.
I believe that if light is not absorbed by a surface, it is mostly reflected. Reflection occurs when incoming solar radiation bounces back from an object or surface that it strikes in the atmosphere, on land, or water, and is not transformed into heat. Not all of the Sun's energy that enters Earth's atmosphere makes it to the surface. The atmosphere reflects some of the incoming solar energy back to space immediately and absorbs still more energy before it can reach the surface. The remaining energy strikes Earth and warms the surface. In contrast, dark earthy surfaces have a low albedo, therefore, they absorb more sunlight. Thus, the proportion of Earth's surface that is covered by ice and snow affects how much of the Sun's solar radiation is absorbed, warming the planet, or reflected. Solar radiation, which includes infrared heat waves and visible light waves, is mostly absorbed by Earth's atmosphere. But due to Earth's reflectivity, or albedo, some of that radiation bounces off of Earth's atmosphere. The sun's rays hit at a flatter angle at higher latitudes, so the solar energy is spread over a wider area. 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. Solar radiation that is not absorbed or reflected by the atmosphere reaches the surface of the Earth. The Earth absorbs most of the energy reaching its surface, a small fraction is reflected. Solar radiation that is not absorbed or reflected by the atmosphere (for example by clouds) reaches the surface of the Earth. The Earth absorbs most of the energy reaching its surface, a small fraction is reflected.
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