Hope this doesn't seem too much like science class, but I found this picture, taken by astronauts aboard the International Space Station, compelling not just for its sheer beauty, but also because of its lucid portrayal of how Earth's atmosphere is layered.
SLIDE SHOW: Sunsets and Other Sky Wonders
Sure, I've bandied about the terms "troposphere" and "stratosphere" -- snuck them into news articles when possible -- but to be honest I've never had a clear picture in my head of what that really looked like. So thanks for the visual, NASA, and here's the explanation of what we're seeing:
This spectacular image of sunset on the Indian Ocean was taken by astronauts aboard the International Space Station (ISS). The image presents an edge-on, or limb view, of the Earth’s atmosphere as seen from orbit. The Earth’s curvature is visible along the horizon line, or limb, that extends across the image from center left to lower right. Above the darkened surface of the Earth, a brilliant sequence of colors roughly denotes several layers of the atmosphere.
Deep oranges and yellows appear in the troposphere, which extends from the Earth’s surface to 6–20 km high. This layer contains over 80 percent of the mass of the atmosphere and almost all of the water vapor, clouds, and precipitation. Several dark cloud layers are visible within this layer. Variations in the colors are due mainly to varying concentrations of either clouds or aerosols (airborne particles or droplets).
The pink to white region above the clouds appears to be the stratosphere; this atmospheric layer generally has few or no clouds, and it extends up to approximately 50 km above the Earth’s surface. Above the stratosphere, blue layers mark the upper atmosphere (including the mesosphere, thermosphere, ionosphere, and exosphere), as it gradually fades into the blackness of outer space.
The ISS was located over the southern Indian Ocean when this picture was taken, with the astronaut looking toward the west.
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