The term "peak wavelength" refers to the color or type of light wave that is most abundant or intense in a given situation or source. It represents the specific length of the wave that has the highest intensity or brightness. Full definition
Slightly before Planck's comprehensive formulation, Wilhelm Wien proposed a «displacement law,» also known as the Wien approx ¬ i ¬ mation, which related peak wavelength (λ) to temperature. (carlineconomics.com)
The team saw a tight correlation between the total energy observed for each blast and the peak wavelength of the measured radiation. (sciencemag.org)
and drops off at wavelengths shorter or longer than the peak wavelength. (astronomynotes.com)