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Direct normal irradiance (DNI), or beam radiation, is measured at the surface of the Earth at a given location with a surface element perpendicular to the Sun direction. [ 6 ] [ failed verification ] It excludes diffuse solar radiation (radiation that is scattered or reflected by atmospheric components).
Direct normal irradiance spectra calculated with SMARTS 2.9.5 for increasing air mass (0 to 10), using the same atmospheric conditions as the ASTM G173 standard. Air mass 0 corresponds to the extraterrestrial spectrum, [1] marked as Top of Atmosphere (TOA).
This is typically specified as average DNI (Direct Normal Irradiance) greater than 5.5-6m kWh/m 2 /day or 2000 kWh/m 2 /yr. Otherwise, evaluations of annualized DNI vs. GNI/GHI (Global Normal Irradiance and Global Horizontal Irradiance) irradiance data have concluded that conventional PV should still perform better over time than presently ...
Reference ranges (reference intervals) for blood tests are sets of values used by a health professional to interpret a set of medical test results from blood samples. Reference ranges for blood tests are studied within the field of clinical chemistry (also known as "clinical biochemistry", "chemical pathology" or "pure blood chemistry"), the ...
Mathematically, for the spectral power distribution of a radiant exitance or irradiance one may write: =where M(λ) is the spectral irradiance (or exitance) of the light (SI units: W/m 2 = kg·m −1 ·s −3); Φ is the radiant flux of the source (SI unit: watt, W); A is the area over which the radiant flux is integrated (SI unit: square meter, m 2); and λ is the wavelength (SI unit: meter, m).
A pyranometer (from Greek πῦρ (pyr) 'fire' and ἄνω (ano) 'above, sky') is a type of actinometer used for measuring solar irradiance on a planar surface and it is designed to measure the solar radiation flux density (W/m 2) from the hemisphere above within a wavelength range 0.3 μm to 3 μm.
Direct neural interface, a brain-computer interface; Direct normal irradiance, a measure of the solar irradiance striking a surface held normal to the line of sight to the sun; Direct normal insolation, also known as direct insolation, a measure of the solar irradiance striking a surface held normal to line of sight to the sun
Thus, for the whole Earth (which has a cross section of 127,400,000 km 2), the power is 1.730×10 17 W (or 173,000 terawatts), [9] plus or minus 3.5% (half the approximately 6.9% annual range). The solar constant does not remain constant over long periods of time (see Solar variation ), but over a year the solar constant varies much less than ...