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4 The Solar Energy Above The Earth's Atmosphere

Author: Source: Datetime: 2016-12-24 12:01:34
The solar constant

The average radius of the earth is only 6.37X103km, which is almost a point relative to the daily-earth mean distance (about 1.50 X 108km), which forms a 32′plane angle with the sun of 1.39X106km in diameter,the solid angle Ωs is:

In the formula, RS is the solar radius; Ds-e is the daily-earth distance.


Geometric Relationships of Day - Earth Mean Distance
Ds - Sun Diameter, 1.39X106km; De - Earth Diameter, 1.27X104km; Ds-e - Day-Earth Distance, 1.50 X 108km

The solar irradiance in the unit solid angle on the upper surface of the Earth's atmosphere is


 Where Ts is the average temperature of the solar surface, 5.6679 X10-8W/(M2•K4) K is the average temperature of the solar surface, Ts is the average temperature of the solar surface, K

The solar irradiance Isc of unit surface area perpendicular to the solar pipeline in the solid angle Ωs of the upper atmosphere of the atmosphere is
From (1-1), we know that σ, Rs, Ts are constant, so Isc is only a function of Ds-e. The eccentricity of the long and short axis of the elliptical orbit of the Earth running around the sun is only 3%, that is, Ds-e is only slightly changed in one year, the change of Isc is only ± 3.5% of the annual average value. Isc is defined as a constant, that is defined in the Japanese - to the average distance of the Earth's atmosphere at the upper boundary perpendicular to the surface of the sun, unit area, unit time received solar radiation energy for the solar constant. In 1981, the World Meteorological Organization (WMO) published the value of the solar constant  Isc = 1368 / M2 =   

8.21 J / ( cm2 min)

Of course, the sun's own activities can also cause fluctuations in solar radiation. But over the years, observations from around the world have shown that the annual amount of solar activity is only about 2.5% higher than the quiet year of solar activity. Therefore, the solar constants can be regarded as the maximum limit of the solar irradiance received on the Earth.

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