Page 113 - Science Course 1 (Book 2)
P. 113
Mo9-L3c: What are the Layers of the Atmosphere?
Combined, the mesosphere and thermosphere are much thicker
than the troposphere and the stratosphere, yet only 1
percent of the atmosphere’s gas molecules are found
in the mesosphere and thermosphere.
Most meteors burn up in the mesosphere
and thermosphere instead of striking Earth.
The ionosphere is a region within the
mesosphere and thermosphere
containing ions.
The ionosphere’s ions ref ect AM radio
waves transmitted at ground level.
Auroras occur in the ionosphere when ions from the The molecules move at incredibly fast speeds after
Sun strike air molecules, causing them to emit vivid absorbing the Sun’s radiation and can escape the
colors of light. pull of gravity and travel into space.
Key Concept
What are the Layers of the Atmosphere?
What are the layers of the atmosphere?
The exosphere is the atmospheric layer farthest
from Earth’s surface where pressure and density are
so low that individual gas molecules rarely strike one
another.
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