Aerosols are indispensable for the formation of clouds. Every water droplet within a cloud has accumulated around a tiny grain of “dust”. Clouds would only form at extremely high humidities if these cores did not exist. Scientists are most interested in the influence of aerosols on the cloud formation in the arctic.
Clouds partly reflect sunlight as well as the outgoing heat radiation of the earth. Like this they affect the radiation balance and can lead to a temperature change on the surface. Therefore aerosols are an important factor for the understanding of our climate.
Aerosols are manifold: They can consist of soot or sulfates from volcano eruptions, bush fires or industries. Also fine sand dust, blown by winds from deserts or sea salt staying in the air after sea spray gets evaporated manifest as aerosols. In addition even bacterias or pollen grains represent aerosols. All these particles have a life time of several days or weeks depending on their size and residence altitude.
During their stay in the atmosphere, particles are carried by winds far from their origin place. Whereas most particles can be found in lower air layers up to 10 km high, other aerosols from volcano eruptions can raise far up into the stratosphere and stay for months. Such an event was recorded by AWIPEV in 2009 after a volcano in Kamtschatka (eastern russia) has released a lot af ashes.