Layers of the Atmosphere
15.1- page 448 / Name:
Use this information to create your foldable organizer about the layers of the atmosphere. / Standard:S6E4 –Students will understand how Earth’s atmosphere is divided into layers.
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Notes
What are the properties of each layer of the atmosphere? How do they vary?
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  • Scientists divide Earth’s atmosphere into five main layers classified according to change in temperature
  • The layers are: Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere
  • Earth’s atmosphere is made of 78% nitrogen, 21% oxygen, 1% carbon dioxide, and other trace gases.
  • Air contains tiny particles of dust, smoke, ice, salt, and chemicals
  • Water vapor is water in gas form. It condenses for form clouds and gives us humidity.
  • At almost 15lb/in2 pressure

Troposphere
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  • *we live in the inner or lowest layer
  • *”Tropo” means turning or changing
  • *Most all of Earth’s weather occurs here
  • *ranges from sea level (0) to 12 km (10 miles) high
  • *shallowest layer but contains almost all of the mass of the atmosphere
  • *as altitude increases, the temperature decreases to about -60o C(-76oF)
  • *water here (at -60o) forms thin feathery clouds of ice (cirrus clouds)

Stratosphere
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  • *extends from the top of the troposphere to about 50 km (32 miles) above the Earth’s surface
  • *”Strato”: means layer or spread out
  • *2nd layer of the atmosphere
  • *contains the ozone layer
  • *as altitude increases, the temperature increases to about 0o C (32oF)
  • *the middle section of the stratosphere contains the ozone layer
  • *ozone absorbs energy from the sun and converts it into heat, warming the air
  • *ozone layer protects Earth’s living things from dangerous ultraviolet (UV rays) radiation
  • Burning fossil fuels gives off carbon dioxide. This creates the pollution that contributes to the depletion of the ozone layer and climate change.

Mesosphere
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  • *3rd layer
  • *”Meso” means middle
  • *begins at 50 km (32miles) and extends to about 80 km (50 miles)
  • *as altitude increases, the temperatures decrease to about -90o C (-130oF)
  • *this layer protects the Earth’s surface from being hit by most meteoroids (chunks of stone and metal from space)
  • *what you see as a shooting star or meteor is the trail of hot, glowing gases the meteoroid leaves behind in the mesosphere

Thermosphere
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  • *4th layer: includes ionosphere and exosphere
  • *air is very thin
  • *from 80 km (50 miles) to about 400 km (250 miles) above the surface
  • *no definite outer limit- but blends gradually into space
  • *”Thermo” means heat
  • *temperatures rise about 1,800o C (3272o F) because the sunlight strikes this layer first
  • *nitrogen and oxygen convert this energy into heat
  • *gas molecules move very rapidly, so the temperature is very high

Ionosphere

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  • *found in the lower layer of the thermosphere
  • *the sun causes the gas molecules to become electrically charged particles called ions
  • *these ions allow radio waves to bounce off of them and back to Earth’s surface.
  • *the Auroras Borealis or Northern Lights are caused by the sun’s rays striking the atoms in the ionosphere causing a glow.

Exosphere
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  • *”Exo” means outer
  • *the exosphere is the last layer and the outer portion of the thermosphere
  • *this is space
  • *extends from about 400 km outward for thousands of kilometers
  • *Only the lightest gases, mainly hydrogen, with some helium and carbon dioxide find their way into the earth’s exosphere
  • *Since the exosphere is technically space, temperatures can reach thousands of degrees Celsius during the day and close to absolute zero(-273.15oC) at night.