Atmospheres on Earth and Venus
Venus and Earth are about the same size and probably started out with similar atmospheres, but now their atmospheres — and climates — are very different.
Earth’s atmosphere contains only about 360 carbon dioxide molecules per million oxygen and nitrogen molecules. Most of the Earth’s carbon is trapped in rocks as carbonates (lime-stones) and organic matter (oil and coal, for example). The atmosphere keeps the Earth’s temperature at an average of 15°C and in a range that allows water to exist with ice and atmospheric water vapor.
On Venus, the atmosphere is predominantly carbon dioxide. Unlike on Earth, little carbon is held in the planet’s rocks. The insulation of Venus by its atmosphere (the green-house effect) results in an average surface temperature of 430°C. Any water on Venus was long ago changed to steam and lost to space.
Topic: Earth Science
Keywords: Earth (Planet), Temperature, Climate, Atmosphere, Climatology, Venus