English: Aerosols are tiny particles, such as soot or dust, suspended in Earth’s atmosphere. In addition to their air quality impacts, aerosols can interfere with sunlight reaching the planet’s surface, which means they play a role in the climate. Remote-sensing scientists often talk about aerosols in terms of their optical depth, which indicates how much of the incoming sunlight aerosols prevent from reaching the Earth’s surface. The global aerosol patterns in 2006 were similar to previous years. High aerosol concentrations were observed over western and central Africa (a mixture of dust from the Sahara and smoke from agricultural fires), northern India (where urban and industrial pollution concentrates against the foothills of the Himalaya Mountains), and northeastern China (urban and industrial pollution). Aerosol optical depth appeared unusually high in 2006 over Indonesia, probably as a result of increased fire activity there. The image also shows the impact of fires in Russia’s boreal forest, which spread aerosols into the Arctic.