The Blue Mountains Eucalyptus Clouds
Known as a favored food of Koalas, eucalyptus trees are a classic feature of the Australian landscape and a symbol of nature down under. Yet few might stop to consider whether eucalyptus trees could contribute to air pollution through their natural release of strong aromatic compounds. The concept of a cloud is familiar: water vapor or even crystals at different concentrations produce the wide variety of forms and colors, including white, light grey, or dark grey. But a remarkable place in Australia offers a much more unusual and ghostly form of cloud activity that has a remarkable biological origin. The blue haze over the Blue Mountains of Australia (named for the phenomena)is attributed to volatile organic compounds released by the trees, including potentially harmful isoprene.