Earth's Fluid Spheres: Atmosphere and Hydrosphere
Classified in Geology
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Just 2.5% of water on Earth is fresh water. About 69% of that fresh water is frozen. This means that less than 1% of water on Earth is drinkable.
1. The Atmosphere
The atmosphere
Earth's gaseous atmosphere is mostly nitrogen & oxygen. It also contains argon, carbon dioxide, ozone & water vapor.
Earth's atmosphere has an upper limit of 10,000 kilometers.
Most of the gases are found in the lowest 15 kilometers.
ATMOSPHERIC PRESSURE
The gases in the atmosphere push down on Earth's surface.
The weight of all these gases is called atmospheric pressure.
We measure atmospheric pressure in standard units called pascals. 1 standard atmosphere = 101.325 pascals.
There is more pressure at lower altitudes, near Earth's surface. There is less pressure at higher altitudes.
2. The Hydrosphere
The hydrosphere
Earth's hydrosphere includes all the water on the planet:
Liquid: most of the water is in the oceans & seas.
Solid: a lot of ice & snow accumulate at Earth's poles.
Gas: water vapor forms clouds in Earth's atmosphere.