udstråle

Udstråle is a Danish verb meaning to emit, radiate, or give off energy, particles, or signals from a source. The corresponding noun udstråling denotes emission or radiation and is used across physics, engineering, meteorology, and biology to describe outward transfer of energy, light, heat, or other substances.

The word is a compound of ud- meaning out and stråle meaning beam or jet. This formation reflects the sense of energy or matter flowing away from a source. In scientific Danish, udstråling is used with various qualifiers such as thermal udstråling, optical udstråling, or radiative udstråling to specify the type of emission.

Applications include physics and engineering, where udstråle describes energy that leaves a body—visible light or infrared radiation from a hot surface, electromagnetic radiation from devices, or acoustic emissions. In environmental science, it can refer to the emission of pollutants or water vapor from a source. In astronomy, udstråling is used to describe the radiative output of stars, protostellar outflows, or active galactic nuclei.

Measurement and theory of udstråling involve radiative transfer concepts. The radiative flux is measured in watts per square meter (W/m^2), and blackbody radiation relates udstråling to temperature via the Stefan-Boltzmann law. Spectral udstråling describes how emission varies with wavelength.

See also: Radiation, Emission, Radiative transfer, Thermal radiation.