Greenhouse Effect: The Planet Where Heat Lingers
The Earth takes in visible sunlight and returns invisible infrared to space. See the planet through infrared eyes, watch CO₂ bend in step with 15 µm light while N₂ ignores it, find the CO₂ bite in the spectrum seen from space, and follow the height the Earth shines from as it rises.
The Earth from space
The Earth’s average temperature is about 15°C. Yet if you work out the temperature of a body that returns to space exactly as much as it takes in from the Sun, you get about −18°C. Where do the missing 33°C come from? That is the question of this expedition. Start with what comes in. About 30% of the sunlight that arrives is bounced straight back to space by clouds, ice, and snow. That fraction is the albedo. Press the surface types in the panel and find where on the Earth light is sent back and where it is swallowed.
Press clouds, ocean, and snow in turn and find, on the globe, what sends light back and what swallows it.
- Whole-planet reflectivity
- 30%
- Sunlight absorbed
- 238 W/m²
- Temperature with no atmosphere
- −18.6°C
- Actual average temperature
- 15°C