Breathe in, breathe out, and focus on these facts about air.

What is air? It most often refers to the Earth’s atmosphere, a mixture of assorted gases and tiny dust particles. Its composition is about 78% nitrogen and 21% oxygen. Tiny amounts of other gases make up the remainder — 0.9% of argon, 0.04% carbon dioxide, along with trace amounts of neon, hydrogen, helium, methane, and krypton.   

    Although air is primarily gases, there are also large quantities of tiny particles referred to as aerosols. These include dust and pollen, but also soot, smoke, and residue from cars and power plants. The air humans breathe also contains upwards of 1,800 different kinds of bacteria.

    The atmosphere around the Earth is divided up into separate layers, based on temperature and height. The first layer closest to our planet is called the troposphere, about 7 miles (11 km) in height. For each 0.6 miles (1 km) ascended into the troposphere, the temperature drops 6 or 7 degrees.

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    The layer above the troposphere is known as the stratosphere, where temperatures stop decreasing, maintaining a temp of around -67 degrees F (-55 C).

    The third layer of air is the mesosphere, about 32 miles (52 km) above Earth. In this layer’s upper section, the mesopause, the temperatures once again start decreasing. Temps are around -130 degrees F (-90 C).

Above the mesosphere, about 56 miles (90 km) above the Earth’s surface, is the thermosphere, where temps actually rise dramatically, reaching 1800 degrees F (1,000 C).

AIR (continued):

    Mountain climbers are well aware of how the air gets “thinner” as they scale the heights, requiring them to carry canisters of oxygen when climbing above 12,500 feet (3,800 m). There’s just not enough oxygen in the atmosphere for them to breathe because there are fewer air molecules at higher altitudes.

You’ve heard the expression “lighter than air,” but it’s by no means light. Its weight pushing down on the Earth’s surface is what creates atmospheric pressure. Air pressure at sea level is high because the whole atmosphere is pushing, but low on a mountaintop because there is less atmosphere pushing down. It’s the difference in air pressure that causes your ears to pop at high altitudes.

    Air serves to insulate the Earth, preventing it from getting too cold or too hot. The gas ozone protects us from too much sunlight. Air also shields us from meteoroids, which, as they enter our atmosphere,    rub against the air and are frequently burned into small pieces.

    When it’s a humid day, it’s because there is a large amount of water in the air. Relative humidity refers to the amount that can be held before it rains. Right before it rains, it reaches the highest level, 100%.

    Humans consume about 13.2 gallons (50 l.) of oxygen per hour. During the process of breathing, called respiration, we take oxygen from the air and give back carbon dioxide. Our lungs put oxygen into the blood, which carries it to your tissues, and cells use it to produce energy. Plants use the carbon dioxide, combined with sunlight, to make food through photosynthesis.

    When the body doesn’t get enough oxygen, whether through an interruption of breathing or an inadequate oxygen supply, asphyxia can be the result, putting the body into unconsciousness and often death. The word asphyxia has its roots in the Latin language, meaning “stopping of the pulse.”