Definition of radiation in English:
1 Physics The emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles that cause ionization.
- Because it uses sound waves instead of radiation, ultrasound is safer than X-rays.
- When taken up by obstacles, beta particles produce a more penetrative secondary radiation known as bremsstrahlung.
- We now know that invisible forces do control some things: gravity, radiation, electricity.
1.1The energy transmitted by radiation, as heat, light, electricity, etc.
- The total spectrum of solar radiation comprises ultraviolet radiations, visible light, and infra-red radiations, in order of increasing electromagnetic wavelengths.
- A radioactive source will emit these radiations at various frequencies, depending on its activity and its decay mode.
- This foil doesn't do very well in the air, but it protected it from meteorites and from the ultraviolet radiations from the sun.
2chiefly Biology Divergence out from a central point, in particular evolution from an ancestral animal or plant group into a variety of new forms.
- Each of these pulses is a major evolutionary radiation of the Theropsid lineage.
- This famous site in British Columbia has yielded much fundamental information on the early radiation of the major animal groups.
- During the Oligocene, the South American rodents began their great evolutionary radiation.
- Example sentences
- On level sites, radiational cooling rather than cold air drainage is most significant in generating the ‘frost pocket’ phenomenon.
- As it stagnates, with the days as long as they are, and the short nights, we don't have the radiational cooling and it just goes on and on.
- When this cloud is present, night-time radiational cooling is much reduced and widespread fog is consequently not usually a problem.
Definition of radiation in:
- British & World English dictionary