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Atmosphere
Atmosphere
• Just like liquids, gases have a density
• Air is composed of different gases
• The air can be heavy & thick (more
dense) or lighter & thinner (less dense)
• The atmosphere is just made up of
different air molecules of varying
densities
Vocabulary
Atmosphere: a mixture of
gases that surround the
Earth
What the Atmosphere is Made Of
Air Density Activity
• Draw a picture of how you think the air
molecules densities change as you go up in
the atmosphere.
• Use dots to represent the air
• Remember that more dense objects are more
crowded.
Pressure Change
Higher Altitude
Lower Altitude
Lower Pressure
Higher Pressure
 Pressure Changes
Vocabulary
• Air Pressure: the weight of
the air.
The Atmosphere
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A layer of gases that surrounds the planet
Makes conditions suitable for life on Earth
Divided into 4 layers
Temperature differences separate the
layers
• Temperature decreases as the altitude
increases (usually)
• The mix of gases affects the
temperature (high or low)
1. THE TROPOSPHERE
• The lowest layer of atmosphere
• Altitude (how high up): from the surface of the
earth up to 20km high
• Where we live
• Where airplanes fly
• Where Earth’s weather and clouds occurs
• Gases mix continuously in this layer
2. THE STRATOSPHERE
• Contains the Ozone layer
• The ozone layer protects life on Earth by
absorbing harmful UV radiation
• Altitude: 20km up to 50km
• Gases are layered and do not mix that much
3. THE MESOSPHERE
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Middle layer of the atmosphere
Coldest layer of the atmosphere
Meteors burn up in this layer
Altitude: 50km up to 85km
4. THE THERMOSPHERE
• Warmest layer because the gases absorb solar
radiation
• Temperature increases as you go higher
• Air is very thin
• Altitude: 86km up to 100,000 km
4a. THE IONOSPHERE
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Lower part of the thermosphere
Not really a layer
Altitude: 86km – 691km
Electrically charged with ions
Reflects AM radio waves and allow them to
travel the world
• Aurora Borealis (Northern Lights) occur in the
lower part of this layer
4b. THE EXOSPHERE
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Outer layer of the thermosphere
Not really a layer
Altitude: 691km – 100,000km
Cold temperature of outer space
Satellites orbit the Earth within this layer.