Cloud Condesation Nuclei (also called CCN's) are critical to the phase change of gaseous water converting to liquid water. These particles are very small, usually 1/100th the size of a cloud droplet. They may be composed of either solid or liquid material. Common CCN's are clay, soot and black carbon from forest fires, sulfate and nitrate particles from factory emissions, and secondary organic matter, such as bacteria. These all serve as nuclei around which water vapor may coalesce and condense into liquid water. CCN's affect climate and relative lifetime properties of clouds. The formation of clouds has a direct relationship to the type and amount of weather an area receives. The answer to your question is "true".