Cloud condensation nuclei

The particles may be composed of dust or clay, soot or black carbon from grassland or forest fires, sea salt from ocean wave spray, soot from factory smokestacks or internal combustion engines, sulfate from volcanic activity, phytoplankton or the oxidation of sulfur dioxide and secondary organic matter formed by the oxidation of volatile organic compounds.

Sulfate and sea salt, for instance, readily absorb water whereas soot, organic carbon, and mineral particles do not.

Additionally, while some particles (such as soot and minerals) do not make very good CCN, they do act as ice nuclei in colder parts of the atmosphere.

[4] Modeling research led by Marcia Baker revealed that sources and sinks are balanced by coagulation and coalescence which leads to stable levels of CCNs in the atmosphere.

[citation needed] Cloud seeding may also occur from natural processes such as forest fires, which release small particles into the atmosphere that can act as nuclei.

[14] Many methods involve the creation of small droplets of seawater to deliver sea salt particles into overlying clouds.

The Revenge of Gaia, written by James Lovelock, an author of the 1987 study, proposes an alternative relationship between ocean temperatures and phytoplankton population size.

[21] By increasing the number of aerosol particles through gas-to-particle conversion processes, the contents of these eruptions can then affect the concentrations of potential cloud condensation nuclei (CCN) and ice nucleating particles (INP), which in turn affects cloud properties and leads to changes in local or regional climate.

[22] This sulphur dioxide undergoes a transformation into sulfuric acid, which quickly condenses in the stratosphere to produce fine sulphate aerosols.

[24] The Earth's lower atmosphere, or troposphere, cools as a result of the aerosols' increased capability to reflect solar radiation back into space.