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Variable > Atmosphere variable > Atmospheric radiation variable > Solar radiation irradiance > Direct normal irradiance

PREFERRED TERM

Direct normal irradiance

TYPE

Variable

DEFINITION

Direct insolation, also known as direct normal irradiance, or its acronym, DNI, 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.
Source: https://en.wikipedia.org/wiki/Direct_insolation

BROADER CONCEPT

Solar radiation irradiance

ENTRY TERMS

Beam radiation
Direct insolation
DNI

CONTRIBUTOR

https://orcid.org/0000-0002-0544-4802

CREATOR

https://orcid.org/0000-0002-0544-4802

HAS CONSTRAINT

HAS OBJECTOFINTEREST

Solar radiation

HAS PROPERTY

Irradiance

SIMPLIFIED LABEL

Direct horizontal irradiance

URI

https://w3id.org/ozcar-theia/c_bd9021ed

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RDF/XML TURTLE JSON-LD Created 1/5/26, last modified 1/5/26