Why is incoming solar radiation in middle latitudes less in winter than in summer and solar radiation strongest around equatorial regions?
Incoming solar radiation in middle latitudes is less in winter than in summer due to the tilt of Earth's axis and its seasonal orbit around the sun. During the winter solstice, the Northern Hemisphere is tilted away from the sun, and the sun's rays strike the Earth at a more oblique angle. This means that the sunlight is spread out over a larger area, resulting in less intense solar radiation. In contrast, during the summer solstice, the Northern Hemisphere is tilted towards the sun, and the sun's rays strike the Earth at a more direct angle. This concentrated sunlight is more intense, resulting in greater solar radiation.
The reason why solar radiation is strongest around the equatorial regions is because these regions receive direct sunlight throughout the year. The equator is tilted at an angle of 23.5 degrees relative to the plane of its orbit around the sun. This means that the sun's rays always strike the equator at a relatively high angle, regardless of the season. As a result, the equatorial regions receive more solar radiation than any other part of the Earth.
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.At higher latitudes, the angle of solar radiation is smaller, causing energy to be spread over a larger area of the surface and cooler temperatures. The insolation reaching any one spot on Earth's surface varies according to latitude and season. Earth is a sphere. This means that the sun's rays hit the different latitudes of Earth at different angles. The angle at which the sun's rays hit the Earth determines the intensity of the solar radiation at that location. The amount of solar radiation varies with latitude because of the curvature of the earth. The temperature decreases from the equator to the poles. This is why the Earth's 23.5 degree tilt is all important in changing our seasons. Near June 21st, the summer solstice, the Earth is tilted such that the Sun is positioned directly over the Tropic of Cancer at 23.5 degrees north latitude. This situates the northern hemisphere in a more direct path of the Sun's energy. The equatorial region receives more solar radiation not only because the Sun's rays hit the region more directly (i.e., at less of an angle), but also because they travel through less of the atmosphere to get there main consequence is that less energy is received in polar regions, so temperatures are cooler. When the sun's rays strike Earth's surface near the equator, the incoming solar radiation is more direct (nearly perpendicular or closer to a 90˚ angle). Therefore, the solar radiation is concentrated over a smaller surface area, causing warmer temperatures. As explained above because of the revolution and Tilt of the Earth, the areas close to the Equator receive maximum solar radiation.The orientation of Earth's surface relative to the Sun's rays diminishes the intensity of solar radiation at high latitudes. The Sun's rays must pass through more atmospheres at higher latitudes. Due to the spherical shape of the Earth, sunlight falls on different parts at different angles. Direct and focused sun rays falls on the equator and hence, the regions here are hotter and warmer. The polar regions receive diffused sun rays, which is why the areas there are colder.
The angular geometry is indeed the main reason. Then you have climatic reasons, related to the occurrence of more cloudiness at mid latitudes than around the sunbelt, in particular.
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