Aitken dust counter

From Glossary of Meteorology
(Redirected from Aitken nucleus counter)



Aitken dust counter

(Or Aitken nucleus counter.) An instrument developed by John Aitken for determining the dust content of the atmosphere.

A sample of air is mixed in an expandable chamber with a larger volume of dust-free air containing water vapor. Upon sudden expansion, the air in the chamber cools adiabatically below its dewpoint, and droplets form with the dust particles as nuclei. A portion of these droplets settle on a ruled plate in the instrument and are counted with the aid of a microscope.
See dust counter.

Aitken, J. 1923. Collected Scientific Papers. 236–246.