Atmospheric aerosols. Computer model showing the mix of particles in the Earth's atmosphere on 23rd August 2018. An aerosol is a suspension of fine solid particles or liquid droplets in the air. These particles are constantly present in the Earth's atmosphere. Here, sea salt aerosols over the ocean are blue, black carbon particles, which are emitted by fires, vehicles and factories, are red, and dust is purple. Imaged by the Goddard Earth Observing System Forward Processing (GEOS FP) model.