Related topics: air pollution · air quality · pollution

Surprising insights about debris flows on Mars

The period that liquid water was present on the surface of Mars may have been shorter than previously thought. Channel landforms called gullies, previously thought to be formed exclusively by liquid water, can also be formed ...

AI making waves in marine data collection

Numerous measurement stations around the world provide us with data about air quality, allowing us to enhance it. Although we are increasingly collecting data from marine areas, access to such data is considerably more challenging. ...

Four most polluted national park sites are in California

A couple years ago, as part of the Sierra Club's Outdoors for All campaign, Roberto Morales took a group of low-income Los Angeles area residents north to Sequoia National Park to help with a forest restoration project.

Smog and sick kids: Thai pupils endure air pollution

Hundreds of Thai children strain to sing the national anthem, reedy voices and fragile lungs competing against eight lanes of belching traffic next to their school's open atrium in central Bangkok.

Earth's atmosphere

The Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by the Earth's gravity. It has a mass of about five quadrillion metric tons. Dry air contains roughly (by volume) 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, and trace amounts of other gases. Air also contains a variable amount of water vapor, on average around 1%. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night.

There is no definite boundary between the atmosphere and outer space. It slowly becomes thinner and fades into space. An altitude of 120 km (75 mi) marks the boundary where atmospheric effects become noticeable during atmospheric reentry. The Kármán line, at 100 km (62 mi), is also frequently regarded as the boundary between atmosphere and outer space. Three quarters of the atmosphere's mass is within 11 km (6.8 mi; 36,000 ft) of the surface.

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