Why solar radiation varies over the Earth's surface and sunlight reaching Earth's Polar Regions different from sunlight reaching Earth's equatorial regions?
The amount of solar radiation that reaches Earth's surface varies over different locations and throughout the year due to several factors, primarily:
Sunlight reaching Earth's polar regions differs significantly from sunlight reaching equatorial regions due to the combined effects of these factors. At the poles, sunlight strikes at a very oblique angle, spreading the radiation over a large area and reducing its intensity. Additionally, polar regions experience shorter daylight hours, further reducing the total solar radiation received. In contrast, equatorial regions receive sunlight at a more direct angle and have longer daylight hours, leading to a higher total solar radiation input.
This variation in solar radiation across different latitudes plays a crucial role in shaping Earth's climate patterns. The equator receives more solar radiation, leading to warmer temperatures, while the poles receive less, resulting in colder temperatures. This differential heating drives atmospheric circulation and ocean currents, influencing weather patterns worldwide.
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. Because the Earth is round, the sun strikes the surface at different angles, ranging from 0° to 90°. The amount and intensity of solar radiation reaching the Earth is affected by the tilt of the Earth's axis and its orientation as it revolves around the Sun. The sun angle at a place varies over the course of the year as a result of the constant tilt and parallelism of the earth's axis. The regions near the equator are hotter than the Polar Regions because direct sunlight falls on the equator region. The Polar Regions receive sunlight at slanted angles, thereby, limiting the amount of solar energy reaching the poles. The equator gets the most direct sunlight year-round. The angle of sunlight hitting the equator is more direct than it is at the poles, so the poles receive less direct sunlight. Sunlight hits a smaller surface area at the Equator so heats up quickly compared to the poles. There are fewer atmospheres to pass through at the Equator compared to the poles. This means more heat from the sun makes it to the surface of the Earth. The factors that cause these variations in insolation are: (i) the rotation of earth on its axis; (ii) the angle of inclination of the sun's rays; (iii) the length of the day; (iv) the transparency of the atmosphere; (v) the configuration of land in terms of its aspect. The last two however, have less influence. Solar radiation at the Earth's surface varies from the solar radiation incident on the Earth's atmosphere. Cloud cover, air pollution, latitude of a location, and the time of the year can all cause variations in solar radiance at the Earth's surface. The Equator receives direct sunlight while Poles receive slant or oblique rays of the Sun. 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. The Earth revolves around the sun in an elliptical orbit and is closer to the sun during part of the year.
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