From Cool Infographics:
Global water and air volume. Conceptual computer artwork of the total volume of water on Earth (left) and of air in the Earth's atmosphere (right) shown as spheres (blue and pink). The spheres show how finite water and air supplies are. The water sphere measures 1390 kilometers across and has a volume of 1.4 billion cubic kilometers. 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 measures 1999 kilometers 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 kilometers of the atmosphere.Or, as stated by Edna St. Vincent Millay:
The world stands out on either side
No wider than the heart is wide;
Above the world is stretched the sky,—
No higher than the soul is high.