Englishfor English speakers
irradiance
noun
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The act of irradiating; emission of rays of light.
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That which irradiates or is irradiated; lustre; splendour; brilliancy.
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physics: Radiant power received by unit area of surface
fluctuation
Noun
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A fluctuation is when something changes back and forth quickly.
The price of wheat stayed the same, but there were a lot of fluctuations in the price of rice.
Every time a cloud goes past, there is a fluctuation in the amount of sunshine.