irradiance

noun

ir·​ra·​di·​ance i-ˈrā-dē-ən(t)s How to pronounce irradiance (audio)
1
2
: the density of radiation incident on a given surface usually expressed in watts per square centimeter or square meter

Examples of irradiance in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Solar irradiance is the amount of power that falls on the surface of the earth, measured in watts per square meter (W/m2). Ian Dexter Palmer, Forbes.com, 10 Sep. 2025 Solar power works for missions close to the sun, but by the time a spacecraft gets to Jupiter, the available solar irradiance drops below 4 percent of that on Earth. IEEE Spectrum, 25 Aug. 2025 Corwin and her colleagues specifically looked at the impact of wildfire smoke on irradiance, or the amount of solar light that makes its way to the surface of a panel. Sharon Udasin, The Hill, 6 Jan. 2025

Word History

First Known Use

1599, in the meaning defined at sense 1

Time Traveler
The first known use of irradiance was in 1599

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Cite this Entry

“Irradiance.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/irradiance. Accessed 1 Oct. 2025.

Medical Definition

irradiance

noun
ir·​ra·​di·​ance ir-ˈād-ē-ən(t)s How to pronounce irradiance (audio)
: the density of radiation incident on a given surface usually expressed in watts per square centimeter or square meter
Last Updated: - Updated example sentences
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