varmeudstrålingen

Varmeudstråling, also known as thermal radiation, is the electromagnetic radiation emitted by all matter with a temperature above absolute zero. This radiation is a fundamental process of heat transfer and occurs at all temperatures, though its intensity increases significantly with temperature. The spectrum of this radiation depends on the temperature of the emitting object. For everyday objects, the radiation is primarily in the infrared part of the electromagnetic spectrum, which is invisible to the human eye. Hotter objects, like incandescent light bulbs or the sun, emit radiation across a wider spectrum, including visible light.

The process of thermal radiation does not require a medium to propagate, meaning it can travel through a vacuum, such as the space between the Sun and Earth. This is in contrast to conduction and convection, which require a physical medium. The amount of energy radiated by an object is determined by its temperature, its surface area, and its emissivity, which is a measure of how effectively the surface emits thermal radiation compared to an ideal black body. Objects with high emissivity radiate more heat. Conversely, objects also absorb thermal radiation from their surroundings. The net heat transfer due to radiation is the difference between the emitted and absorbed radiation. This phenomenon plays a crucial role in many natural and technological processes, from the warming of the Earth by the sun to the operation of thermal imaging cameras.