What is the maximum solar radiation on Earth and high latitudes receive less solar radiation the top of the atmosphere than low latitudes on an annual basis?
The maximum solar radiation on Earth is approximately 1,361 watts per square meter (W/m²) at the top of the atmosphere. This value, known as the solar constant, represents the average amount of solar energy that reaches Earth's outer atmosphere. However, the actual amount of solar radiation that reaches Earth's surface varies depending on several factors, including the time of year, latitude, cloud cover, and atmospheric conditions.
High latitudes receive less solar radiation than low latitudes on an annual basis due to the Earth's tilt. The Earth's axis is tilted at an angle of 23.5 degrees relative to its plane of orbit around the Sun. This tilt causes the Sun's rays to strike different parts of the Earth at different angles throughout the year. As a result, high latitudes receive more direct sunlight during the summer months, when the Sun is high in the sky, and less direct sunlight during the winter months, when the Sun is low in the sky.
In addition to the Earth's tilt, atmospheric conditions can also affect the amount of solar radiation that reaches Earth's surface. Clouds, for example, can reflect and scatter sunlight, reducing the amount of solar energy that reaches the ground. Atmospheric aerosols, such as dust and pollution, can also absorb and scatter sunlight, further reducing the amount of solar energy that reaches the ground.
As a result of these factors, the actual amount of solar radiation that reaches Earth's surface can vary widely from place to place and from time to time. However, in general, high latitudes receive less solar radiation than low latitudes on an annual basis.
At latitudes near the equator the Earth's surface is almost directly perpendicular to the angle of the sun's rays. In these regions, solar radiation is intense because the sun's energy is concentrated over a small surface area. The maximum recorded direct solar radiation on the surface of the earth is 1050 W/m2. The maximum global radiation on a horizontal surface at ground level has been recorded is 1120 W/m2. Above the earth's atmosphere, solar radiation has an intensity of approximately 1380 watts per square meter (W/m2). This value is known as the Solar Constant. At our latitude, the value at the surface is approximately 1000 W/m2 on a clear day at solar noon in the summer months. In contrast, those in higher latitudes receive sunlight that is spread over a larger area and that has taken a longer path through the atmosphere. As a result, these higher latitudes receive less solar energy. 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 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. The angle at which the Sun's rays strike the Earth changes from the equator toward the poles. The result is that incoming solar radiation decreases with latitude. More solar radiation is received in the tropics than at the poles, resulting in an equator-to-pole temperature gradient. One of the key reasons more warming occurs at high latitudes – even in the absence of sea ice – is the absence of convection at high latitudes. Convection occurs when air close to the ground is heated by the warm surface of the Earth. The warmed air is lighter than the cold air above and so starts to rise.
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