Composition of the Atmosphere

The Earth's atmosphere is made up of approximately 78 percent nitrogen, 21 percent oxygen, and small amounts of argon, carbon dioxide, neon, helium, krypton, hydrogen, ozone and traces of other gases.

Although its composition is the same at sea level and at great heights, except for water vapor and some impurities, the air becomes less dense at higher altitudes

In addition to these gases, the atmosphere is also full of inanimate matter such as dust, soot, volcanic ash, salt crystals from sea spray and fine sand grains raised by storms in the deserts.

In addition, two to three thousand tons of cosmic dust falls from space and into the Earth's atmosphere each day

The atmosphere is full of life. An enormous number of plants and animals, including human beings, live in the densest bottom layer. It is a zone full of flowering, breathing and growing creatures.

There is also an abundance of life above this layer.

Up to a height of about six miles, the air is full of suspended bacteria, fungal spores and pollen grains.

Between 2500 and 4500 feet, a cube of air the size of a lump of sugar contains an average of about 70 microorganisms, including mold spores, cocci and yeast species.