Radiometric

Radiometric refers to radiometry, the measurement of electromagnetic radiation. Radiometry quantifies the magnitude of radiant energy in absolute terms, across wavelengths, and without regard to how the human eye perceives light. It is contrasted with photometry, which weights measurements by the eye's sensitivity.

Key quantities include radiant flux (power in watts), irradiance (W/m^2), radiance (W/(sr·m^2)), and spectral radiance. Measurements rely on instruments such as radiometers and spectroradiometers, calibrated against traceable standards, often using blackbody sources and detectors.

Radiometric dating uses radioactive decay to estimate ages of materials. It relies on known half-lives and initial conditions. Common methods include carbon-14 dating for organic materials up to about 50,000 years, uranium-lead dating for rocks and minerals millions to billions of years, and potassium-argon dating for volcanic materials. Accuracy depends on contamination, decay constants, and closed-system conditions.

Applications span remote sensing, astronomy, environmental monitoring, geology, and materials testing. Radiometric techniques underpin sensor calibration and atmospheric measurements, enabling comparisons across instruments and over time.