Radiatív

Radiatív is a term used in physics and related disciplines to describe phenomena that involve radiation, particularly electromagnetic radiation. It is derived from the concept of radiation as energy carried by waves or particles, and is used in several languages to denote radiative processes.

In physics, radiative processes include the emission, absorption, and scattering of photons by matter. Atomic and molecular transitions emit or absorb photons, giving rise to spectra that reveal the properties of the emitting body. Spontaneous and stimulated emission are important mechanisms in lasers and fluorescence, while absorption and scattering shape how light interacts with materials. The radiation spectrum of a body depends on its temperature and composition, with blackbody radiation described by Planck's law.

Radiative heat transfer is the transfer of thermal energy by photons between bodies, which can occur across a vacuum or transparent medium. It depends on temperature, surface emissivity, and spectral properties of the material. The Stefan-Boltzmann law applies to idealized blackbodies, while real surfaces are described by emissivity less than one. Kirchhoff's law links emissivity and absorptivity at thermal equilibrium, providing a link between how a surface emits and absorbs radiation.

The radiative transfer concept models how radiation travels through a medium, taking into account absorption, emission, and scattering. The radiative transfer equation describes the change in radiant intensity along a path, influenced by the medium's opacity and internal sources. This framework is essential in fields ranging from astronomy and cosmology to atmospheric science and engineering.

Applications of radiatív include studying astronomical light, analyzing the greenhouse effect in Earth's atmosphere, and designing thermal systems that rely on radiative heating or cooling. Non-radiative energy transfer, by contrast, occurs through conduction or convection and does not involve photons.