What is the atmosphere?

On Earth, the atmosphere is the blanket of gasses surrounding our planet.

The atmosphere is composed of 78% Nitrogen, 21% Oxygen, 0.9% Argon, 0.03% Carbon Dioxide, and other gasses such as water vapor. There are also dust particles, pollen, plain grains and other solid particles.

The atmosphere is about 300 miles thick, but most of it is contained within the first 10 miles or so from Earth's surface. Our atmosphere is separated into 5 main layers:

  • Troposphere: The layer closest to Earth's surface (about 4-12 miles thick). This is where nearly all of the water vapor and dust particles exist, which is why clouds form. This layer contains all of Earth's weather.
  • Stratosphere: The stratosphere begins after the troposphere and ends around 31 miles above ground. This layer is where the Ozone Layer exists. The air here is also very dry and much thinner, so planes and hot air balloons fly closer to the stratosphere.
  • Mesosphere: The mesosphere is above the stratosphere and extends to around 53 miles high. The top of this layer is the coldest part of Earth's atmosphere and meteors burn up in this layer.
  • Thermosphere: This layer is above the mesosphere and is the hottest layer of Earth's atmosphere. It extends to about 310-620 miles above Earth's surface. With such low air density here, sometimes this layer is thought of as part of outer space.
  • Exosphere:This very thin layer is the upper limit of our atmosphere and is where Earth's atmosphere merges into outer space.


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Historical Averages

High Low
Current 65°F 50°F
Average 40°F 22°F
Record 68°F February 20, 1930 -2°F February 20, 1936