What is Radioactive Fallout?
- Fallout is the residual radiation hazard from a nuclear explosion, so named because it "falls out" of the atmosphere into which it is spread during the explosion. It commonly refers to the radioactive dust created when a nuclear weapon explodes. Visible dust is referred to as “local” or close-in fallout. Very small particles (not visible) is referred to as delayed or “world wide” fallout.
- Early, Local or Close-in Fallout – Made up of visible particles, e.g., fine sand, ~ ≤100 microns at the most distant portions of the fallout area to larger particles closer in to point of burst.
- Delayed or Worldwide Fallout – This the deposition of very small particles which descend very slowly over large areas of the earth's surface.
Behavior of Fallout
- Energy or Yield
- Design of the weapon/device
- Height of the Explosion
- Nature of surface beneath point of burst.
- Meteorological conditions: Height of Tropopause, Temperature, Precipitation, Wind speed, Wind Direction, Wind shear.
- The tropopause is the atmospheric boundary between the troposphere (~6.8 mi., or ~12 km) and the stratosphere.