Friday, January 30, 2009

All the Water and Air on Earth

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), shown on the same scale as the Earth.

Left: All the water in the world including sea water, ice, lakes, rivers, ground water, clouds, etc. This sphere 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.

Right: All the air in the atmosphere gathered into a ball at sea-level density. This sphere 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.

(from here)


Anonymous said...

I thought we can get new water from outer space.

Also, plenty of ice asteroids out there.

Anonymous said...

People have a mistaken sense of how high the mountains are and how deep the oceans are. If you held Earth in the palm of your hand you would not even be able to feel the mountains. Earth is smooth as a cue ball. There'd be a microscopically thin layer of bumps and damp valleys on the ball in your hand.

You can realize this easily be bringing to mind the pictures of Earth taken from space and visualizing the outline presented. It's a perfect circle, right? No big dimples or bumps. Same with lunar eclipses; the shadow of Earth on the moon is a beautiful curved segment of a circle. This makes sense with how the planets were formed and why they are round in the first place (gravity pulling equally on all parts), but it doesn't accord with our intuitive sense of the "great" size of mountains and depth of oceans. In reality there's just a thin film of scum on a very smoothly round rock, with lifelessness below and above.

And above is thin too. Space is intuitively thought of as far away, but it isn't. If you're in Brooklyn, space is closer to you than Lakewood is. If you could point your car straight up and drive at 60 mph, you'd be in space in about an hour!

Anonymous said...

and also how much dirt there is under our feet.