Welcome to the Greenhouse
Earth’s atmosphere works like a greenhouse, trapping heat from the sun to turn our planet into the brown-green-blue-white Earth it is today.
To understand the Greenhouse effect, we have to understand something about the structure and content of our atmosphere and solar radiation. Clouds and surface albedo play a smaller role.
Layers of the Atmosphere
Our atmosphere is a layered, gaseous shell. Gravity hugs atoms, molecules, and particles close to the earth. In return, the atmosphere keeps us warm, shields us from UV radiation, and regulates the planet’s temperature.
From the earth’s surface to 10km altitude sits the troposphere. Most clouds form in the troposophere – since a vast majority (99%!) of the earth’s water vapour is here. It’s the densest layer of the atmosphere, and where almost all weather occurs.
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From there, we go down in density and up in altitude to the stratosphere, where the ozone layer protects us UV rays and most planes fly, to the mesosphere where the air is too thin to breathe, and finally up to the thermosphere. The exosphere (sometimes differentiated from the thermosphere) is the transition from earth’s atmosphere into space; there is no hard boundary.
Components of the Earth’s atmosphere
Earth’s atmosphere is primarily composed of nitrogen (78%) and oxygen (21%), followed by argon, carbon dioxide, and other gasses. Water vapor makes up an average of 1% of the atmosphere. Aerosols - fine particles like pollen, dust, salt, and smoke - also reside in the atmosphere, sometimes serving as condensation nuclei for clouds.
Learn more: UCAR Center for Science Education. “Layers of the Atmosphere.” https://scied.ucar.edu/learning-zone/atmosphere/what-is-atmosphere
Pair with: Exxon 1982 Report on CO2 Greenhouse Effect from Inside Climate News, The Calculating Stars by Mary Robinette Kowal, and feral.earth
Return to syllabus
In case you ever feel lost, or want to jump, here’s a map.