Condensation Nuclei
Typical Atmospheric Number Density: 103 - 104 /cm3
Mass Range: > 10-12 gram
Common Substances: dust, smoke, salt, sulfate particles from phytoplankton, pollutants
| Condensation Nuclei Classification Criteria | ||
| Classified by | Type | Characteristics |
| (1) Size | Small Aitken | r < 0.2 μm (10-6 m) |
| Large Aitken | 0.2 μm £ r £ 1.0 μm | |
| Giant Aitken | r > 1.0 μm | |
| (2) Interaction with water vapor | Hygroscopic ("water seeking") |
Condensation can occur for RH
< 100% (down to about 75%), e.g., salt |
| Hydrophobic ("water repelling") |
Condensation occurs only at RH
> 100%, e.g., oils, paints |
|
Usually a wide mixture of particle types and sizes are present. Hence haze, fog and clouds typically form at RH < 100%.