fallout


fallout
/fawl"owt'/, n.
1. the settling to the ground of airborne particles ejected into the atmosphere from the earth by explosions, eruptions, forest fires, etc., esp. such settling from nuclear explosions (radioactive fallout). Cf. rainout.
2. the particles themselves. Cf. rainout.
3. an unexpected or incidental effect, outcome, or product: the psychological fallout of being obese.
4. effects; results: emotional fallout from a divorce.
Also, fall-out.
[1945-50; n. use of v. phrase fall out]

* * *

Descent of radioactive materials from the atmosphere to the earth.

Radioactivity in the atmosphere may arise from natural causes such as cosmic rays as well as from nuclear explosions and atomic reactor operations. The explosion of nuclear weapons leads to three types of fallout: local, tropospheric, and stratospheric. The first, intense but relatively short-lived, occurs as larger radioactive particles are deposited near the site of the explosion. Tropospheric fallout occurs when the finer particles enter the troposphere, and it spreads over a larger area in the month after the explosion. Stratospheric fallout, made of fine particles in the stratosphere, may continue years after the explosion, and the distribution is nearly worldwide. Many different radioisotopes are formed during a nuclear explosion, but only long-lived isotopes (e.g., cesium-137, strontium-90) are deposited as stratospheric fallout.

* * *

      deposition of radioactive materials on the Earth from the atmosphere. The terms rain out and snow out are sometimes used to specify such deposition during precipitant weather.

      Radioactivity in the atmosphere may arise from (1) natural causes, (2) nuclear (nuclear weapon) or thermonuclear bomb explosions, and (3) induced radioactivities and fission products from atomic reactor operations.

      Most of the natural radioactivity in the atmosphere is a result of cosmic rays and the gaseous diffusion of radon from natural uranium and thorium found in the Earth's crust. The local concentrations of these gases in the atmosphere depend to a great extent on the distribution of uranium and thorium in the Earth, as well as on meteorological conditions. Cosmic rays produce, among other isotopes, radioactive forms of carbon and hydrogen.

      The explosion of nuclear bombs that release radioactivity leads to three separate types of fallout: local, tropospheric, and stratospheric. The local fallout is due to the deposition of the larger radioactive particles near the site of the explosion. This fallout is quite intense but relatively short-lived. Tropospheric fallout occurs when the finer particles enter the troposphere (the lower part of the Earth's atmosphere) and are deposited at a later time and over a larger area, depending on the local meteorological conditions. In general, tropospheric fallout occurs in the month following the explosion and takes place in the general latitude of the explosion site. Stratospheric fallout, made up of extremely fine particles in the stratosphere (above the troposphere), may continue years after the explosion, and the distribution is nearly worldwide. Generally only large nuclear weapons produce significant stratospheric fallout.

      Many different radioisotopes are formed during a nuclear explosion, but only the long-lived isotopes are deposited as stratospheric fallout. Examples are cesium-137 and strontium-90, which have 27- and 28-year half-lives. The latter presents the greater hazard to animal life since it is chemically similar to calcium and may replace the calcium in certain foods and ultimately become concentrated in the body. The radioactive material in the stratosphere eventually mixes with the troposphere, where it then deposits out onto the Earth through electrical attraction or gravity or by attachment to larger particles such as water droplets.

* * *


Universalium. 2010.

Look at other dictionaries:

  • Fallout 3 — Обложка русскоязычного издания Разработчик Bethesda Game Studios Издатели Америка …   Википедия

  • Fallout 3 — Entwickler …   Deutsch Wikipedia

  • Fallout — Разработчик Black Isle Studios Издатель Interplay Entertainment …   Википедия

  • Fallout 3 — Éditeur Bethesda Softworks Développeur Bethesda Game Studios Début …   Wikipédia en Français

  • Fallout — Saltar a navegación, búsqueda Fallout Desarrolladora(s) Black Isle Distribuidora(s) Interplay Fecha(s) de lanzamiento 1997 …   Wikipedia Español

  • Fallout 2 — Entwickler …   Deutsch Wikipedia

  • Fallout II — Fallout 2 Fallout 2 Éditeur Interplay Développeur Black Isle Studios …   Wikipédia en Français

  • Fallout 2 — Éditeur Interplay Développeur Black Isle Studios …   Wikipédia en Français

  • Fallout — Éditeur Interplay Développeur Black Isle Studios Concepteur …   Wikipédia en Français

  • Fallout — may refer to: *Nuclear fallout, the residual radiation hazard from a nuclear explosion. * Fallout (video game), a 1997 post apocalyptic computer role playing game released by Interplay Entertainment. ** Fallout series, the sequels and spinoff… …   Wikipedia

  • Fallout — (aus engl. fallout) wird in folgenden Zusammenhängen verwendet: Fallout im Sinne von radioaktiver Niederschlag Der Auswurf fester Bestandteile (Pyroklastika) bei einem Vulkanausbruch wird als Airfall beziehungsweise Fallout bezeichnet nach… …   Deutsch Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.