The size distribution of aerosol arriving at the South Pole was measured several times during four days of relatively homogeneous meteorological transport conditions. This aerosol had a maximum number concentration in the 10-6cm-6cm radius range, and a maximum volume concentration in the 2¿10-5-2¿10-4cm radius range, a total number concentration of 106/cm3 and a total volume concentration of 10-6cm3/m3, which would correspond to a mean mass concentration of about 1--2 &mgr;m/m3. Almost all particles of r?1.5¿10-5cm were hygroscopic, with refractive index near 1.54. No particles of r?6¿10-4cm were found in 75m3 of air, and an average of 44/cm3 carried charges.

This aerosol represents the background aerosol which occurs at the end point of a long series of meteorological precipitation processes; aerosols suffering a similar chain of processes while being transported vertically in the troposphere may also approach the same end point.