Previous Year Question
‘Pyrheliometer’ is used for measuring:
Sun spots
Solar radiation
Air temperature
Temperature of plants
Correct Answer: B
Detailed Solution
A Pyrheliometer is an instrument used to measure Direct Solar Radiation or Direct Solar Irradiance received directly from the Sun.
It is oriented towards the Sun so that the solar rays fall approximately at normal incidence on the receiving surface of the instrument.
The measurement is generally expressed in Watts per square metre (W/m²).
It is useful to distinguish between a Pyrheliometer and a Pyranometer. A Pyrheliometer primarily measures direct-beam solar radiation, whereas a Pyranometer is generally used to measure global solar radiation received on a horizontal surface, including the combined effect of direct and diffuse components.