irradiance

noun

ir·​ra·​di·​ance i-ˈrā-dē-ən(t)s 

1

: radiance sense 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

The researchers modeled solar variability using a normal distribution with a mean of 80% of nominal irradiance and a standard deviation of 12% to capture seasonal and diurnal shifts. —Aman Tripathi, Interesting Engineering, 26 Nov. 2025

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

Word History

First Known Use

1599, in the meaning defined at sense 1

Rhymes for irradiance

• radiance

Medical Definition

irradiance

noun

ir·​ra·​di·​ance ir-ˈād-ē-ən(t)s 

: the density of radiation incident on a given surface usually expressed in watts per square centimeter or square meter