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Direct Insolation
Direct insolation is the insolation measured at a given location on Earth with a surface element perpendicular to the Sun's rays, excluding diffuse insolation (the solar radiation that is scattered or reflected by atmospheric components in the sky). Direct insolation is equal to the solar irradiance above the atmosphere minus the atmospheric losses due to absorption and scattering. While the solar irradiance above the atmosphere varies with the Earth–Sun distance and solar cycles, the losses depend on the time of day (length of light's path through the atmosphere depending on the solar elevation angle), cloud cover, humidity, and other impurities. Simplified formula A simple formula gives the approximate level of direct insolation when there are no clouds: :I_D=1.353\text^2\times 0.7^ where ''AM'' is the airmass given by :AM=\frac 1 with θ being the zenith angle (90° minus the altitude) of the sun. For the sun at the zenith, this gives 947 W/m2. However, anothe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insolation
Solar irradiance is the power per unit area ( surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m2) in SI units. Solar irradiance is often integrated over a given time period in order to report the radiant energy emitted into the surrounding environment (joule per square metre, J/m2) during that time period. This integrated solar irradiance is called solar irradiation, solar exposure, solar insolation, or insolation. Irradiance may be measured in space or at the Earth's surface after atmospheric absorption and scattering. Irradiance in space is a function of distance from the Sun, the solar cycle, and cross-cycle changes.Michael Boxwell, ''Solar Electricity Handbook: A Simple, Practical Guide to Solar Energy'' (2012), p. 41–42. Irradiance on the Earth's surface additionally depends on the tilt of the measuring surface, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
