Unit 9: The Atmosphere
What Earth's air is actually made of and how it's layered by temperature, from the ground you breathe on up to the edge of space.
4 topics · 13 questions
Each topic is a path, not a menu: work down it in order and every question builds on the one above. Click any of them to watch the answer draw itself.
Composition of Earth's Atmosphere
- How it worksHow do nitrogen, oxygen, and trace gases like carbon dioxide and water vapor combine to make up Earth's atmosphere?
- Common mistakeWhy isn't carbon dioxide a large percentage of Earth's atmosphere, even though it matters so much for climate?
- Ties togetherHow does the atmosphere's balance of gases connect to the greenhouse effect that keeps Earth warm?
Your turn1 of 2
Earth's atmosphere is about 78 percent nitrogen and about 21 percent oxygen by volume. In a sample of 727 liters of air, about how many more liters are nitrogen than oxygen?Layers of the Atmosphere
- How it worksHow does temperature rising and falling in bands divide the atmosphere into the troposphere, stratosphere, mesosphere, and thermosphere?
- How it worksWalk me through what happens to a rising weather balloon's temperature as it climbs from the ground into the stratosphere.
- Common mistakeWhy doesn't temperature just keep dropping the higher you go through every layer of the atmosphere?
- Going furtherWhat layer of the atmosphere gets warmed directly by the ozone layer absorbing ultraviolet radiation?
Your turn1 of 2
In the troposphere, temperature drops by roughly 6 degrees Celsius for every kilometer of altitude gained. Starting from a ground temperature of 20 degrees Celsius, about what temperature would you expect at an altitude of 9 kilometers?Atmospheric Pressure
- How it worksHow does the weight of the entire column of air above you create atmospheric pressure that drops with altitude?
- Worked exampleFind roughly what atmospheric pressure drops to at the summit of Mount Everest compared with sea level's 1013 millibars.
- Common mistakeWhy doesn't atmospheric pressure decrease at a constant rate all the way up through the atmosphere?
Your turn1 of 2
Atmospheric pressure at sea level is about 1013 millibars and roughly halves for every 5.5 kilometers of altitude gained. About what pressure, in millibars, would you expect after 3 such halvings?Solar Radiation and the Atmosphere's Energy Budget
- How it worksHow does incoming solar radiation balance against outgoing heat radiated back to space to set Earth's energy budget?
- How it worksWalk me through sunlight being absorbed, reflected, and re-radiated as it moves through Earth's energy budget.
- Ties togetherHow does albedo change the fraction of incoming sunlight that Earth reflects instead of absorbing?
Your turn1 of 2
Earth's albedo, the fraction of incoming sunlight it reflects rather than absorbs, is about 33 percent. Out of 684 units of incoming solar energy, about how many units does Earth absorb rather than reflect?