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The angular diameter of the Earth as seen from the Sun is approximately 1/11,700 radians (about 18 arcseconds), meaning the solid angle of the Earth as seen from the Sun is approximately 1/175,000,000 of a steradian. Thus the Sun emits about 2.2 billion times the amount of radiation that is caught by Earth, in other words about 3.846×10 26 watts.
The actual figure varies with the Sun's angle and atmospheric circumstances. Ignoring clouds, the daily average insolation for the Earth is approximately 6 kWh/m 2 = 21.6 MJ/m 2. The output of, for example, a photovoltaic panel, partly depends on the angle of the sun relative to the
The solar constant is defined for the Sun's radiation at the distance to the Earth, also known as one astronomical unit (au). Consequently, at a distance of R astronomical units ( R thus being dimensionless), applying the inverse-square law , we would find: P = G SC c R 2 cos 2 α . {\displaystyle P={\frac {G_{\text{SC}}}{cR^{2}}}\cos ^{2 ...
The solar constant is equal to approximately 1,368 W/m 2 (watts per square meter) at a distance of one astronomical unit (AU) from the Sun (that is, at or near Earth's orbit). [99] Sunlight on the surface of Earth is attenuated by Earth's atmosphere , so that less power arrives at the surface (closer to 1,000 W/m 2 ) in clear conditions when ...
At fixed latitude, the size of the seasonal difference in sun angle (and thus the seasonal temperature variation) is equal to double the Earth's axial tilt. For example, with an axial tilt is 23°, and at a latitude of 45°, then the summer's peak sun angle is 68° (giving sin(68°) = 93% insolation at the surface), while winter's least sun ...
The earth's atmosphere absorbs a considerable amount of the ultraviolet light. The resulting spectrum at the Earth's surface has fewer photons, but they are of lower energy on average, so the number of photons, above the bandgap, per unit of sunlight energy is greater than in space. This means that solar cells are more efficient at AM1 than AM0.
The total solar energy absorbed by Earth's atmosphere, oceans and land masses is approximately 122 PW·year = 3,850,000 exajoules (EJ) per year. [12] In 2002 (2019), this was more energy in one hour (one hour and 25 minutes) than the world used in one year. [13] [14] Photosynthesis captures approximately 3,000 EJ per year in biomass. [15]
A 2021 publication [8] about solar geometry first calculates the x-, y-, and z-component of the solar vector, which is a unit vector with its tail fixed at the observer's location and its head kept pointing toward the Sun, and then uses the components to calculate the solar zenith angle and solar azimuth angle. The calculated solar vector at 1 ...