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Examoogle • User • info@examoogle.com • EE-2024-8821
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A pyrometer is used for the measurements of
Diffuse radiations only
Direct radiations only.
Both direct and diffused radiations.
None of the above.
Both direct and diffused radiations.
Quick Summary: A pyranometer is an actinometer used to measure the total solar irradiance on a planar surface. It measures both the direct beam radiation coming from the sun and the diffuse sky radiation resulting from the scattering of sunlight in the atmosphere.
A pyranometer is an actinometer used to measure the total solar irradiance on a planar surface. It measures both the direct beam radiation coming from the sun and the diffuse sky radiation resulting from the scattering of sunlight in the atmosphere.
Iglobal=Ibeam+Idiffuse — Sum of direct and diffuse components
Vout=S×Iglobal — S is the sensitivity constant of the pyranometer
The sensor typically utilizes a thermopile or a photodiode mounted under two concentric glass domes. The domes protect the sensor and ensure the cosine response is maintained while limiting the spectral range. The radiation absorbed creates a temperature difference across the thermopile junctions, generating a small voltage proportional to the total incident solar flux (Itotal=Ibeam+Idiffuse).
Pyranometers measure solar irradiance in W/m2.
They are distinct from pyrheliometers, which measure ONLY direct beam radiation using a collimated tube.
The glass dome ensures the measurement follows the Lambert's Cosine Law.
Typically used in meteorological stations and solar power plant performance monitoring.
Measures the total energy available for PV conversion
Essential for assessing overall solar plant performance
Requires regular cleaning to prevent dust accumulation
Sensitivity can drift over long periods
Solar Photovoltaic (PV) system efficiency monitoring
Agrometeorology and climatological research
A pyrheliometer measures only the direct beam component of solar radiation by utilizing a narrow field of view.
Option B refers to the measurement capability of a pyrheliometer.
C is correct — A pyranometer is designed to measure the total solar radiation incident on a flat surface, which includes both the direct beam radiation and the diffuse radiation scattered by the atmosphere.
Always remember the suffix: -meter usually implies measurement; 'pyrheliometer' targets the 'helios' (sun) beam directly, while 'pyranometer' covers the whole 'pyr' (fire/radiation) hemisphere.