This view of Earth's horizon as the sun sets over the Pacific Ocean was taken on 21 July 2003 by an Expedition 7 crewmember onboard the International Space Station (ISS). Anvil tops of thunderclouds are also visible.
Click on image for full size
Courtesy of NASA Human Space Flight Collection

Atmospheric Science Literacy - Essential Principle 1

Earth has a thin atmosphere that sustains life.

Fundamental Concept 1.1
Earth's atmosphere is a mixture of gases with small, but important, quantities of liquid and solid particles.

Fundamental Concept 1.2
The atmosphere has mass, is bound to Earth by gravity, and exerts pressure which is greater near Earth's surface and decreases with altitude.

Fundamental Concept 1.3
The atmosphere, which is very thin relative to Earth's radius, varies vertically in layers which differ in composition, density, and temperature. The lowest 8-16 km of the atmosphere - the troposphere - contains most of Earth's weather systems.

Fundamental Concept 1.4
Earth's atmosphere sustains and protects living things. Its composition has changed over time, as it has been influenced by life and by geological and geochemical processes. Through photosynthesis, plants produce the oxygen in the atmosphere that makes life possible.

Fundamental Concept 1.5
Other bodies in the Solar System also have atmospheres. Their composition and motions vary considerably from those of Earth's atmosphere due to planetary size, place in the Solar System, speed of rotation, and other planetary processes.

Last modified July 29, 2009 by Becca Hatheway.

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