... gathered into spheres and compared to the Earth.
The water sphere (blue) in this computer visualization measures 1390 kilometres across and has a volume of 1.4 billion cubic kilometres. This includes all the water in the oceans, seas, ice caps, lakes and rivers as well as ground water, and that in the atmosphere. The air sphere (pink) measures 1999 kilometres across and weighs 5140 trillion tonnes. As the atmosphere extends from Earth it becomes less dense. Half of the air lies within the first 5 kilometres of the atmosphere. The spheres show how finite water and air supplies are.
Created by Adam Nieman / Science Photo Library. Via BoingBoing.