Chapter 1 – The Composition and Structure of the Atmosphere.
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Transcript of Chapter 1 – The Composition and Structure of the Atmosphere.
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Chapter 1 – The Composition and Structure of the Atmosphere
![Page 2: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/2.jpg)
Terms and Definitions• Atmosphere – The mixture of gases, water
droplets, and solid particles above the earth’s surface
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Terms and Definitions• Atmosphere – The mixture of gases, water
droplets, and solid particles above the earth’s surface
• Weather – Short-term atmospheric phenomena lasting from hours up to about a week (e.g. thunderstorms, hurricanes, periods of high winds, drizzle)
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Terms and Definitions• Atmosphere – The mixture of gases, water
droplets, and solid particles above the earth’s surface
• Weather – Short-term atmospheric phenomena lasting from hours up to about a week (e.g. thunderstorms, hurricanes, periods of high winds, drizzle)
• Climate – Long-term atmospheric conditions lasting from weeks to years (e.g. average yearly Lubbock precipitation, global warming)
![Page 5: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/5.jpg)
Terms and Definitions• Atmosphere – The mixture of gases, water
droplets, and solid particles above the earth’s surface
• Weather – Short-term atmospheric phenomena lasting from hours up to about a week (e.g. thunderstorms, hurricanes, periods of high winds, drizzle)
• Climate – Long-term atmospheric conditions lasting from weeks to years (e.g. average yearly Lubbock precipitation, global warming)
• Meteorology – The study of weather
![Page 6: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/6.jpg)
Terms and Definitions• Atmosphere – The mixture of gases, water droplets,
and solid particles above the earth’s surface
• Weather – Short-term atmospheric phenomena lasting from hours up to about a week (e.g. thunderstorms, hurricanes, periods of high winds, drizzle)
• Climate – Long-term atmospheric conditions lasting from weeks to years (e.g. average yearly Lubbock precipitation, global warming)
• Meteorology – The study of weather
• Climatology – The study of climate
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Thickness of the Atmosphere
• How high is the atmosphere?• No defined top
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Thickness of the Atmosphere
• How high is the atmosphere?• No defined top• 99.99997% of atmosphere is below 100 km (60 mi)
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Thickness of the Atmosphere
• How high is the atmosphere?• No defined top• 99.99997% of atmosphere is below 100 km (60 mi)• Weather occurs in lowest 11 km (7 mi)
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Thickness of the Atmosphere
• How high is the atmosphere?• No defined top• 99.99997% of atmosphere is below 100 km (60 mi)• Weather occurs in lowest 11 km (7 mi)• Atmospheric depth is very thin relative to earth’s
horizontal distances
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The Evolution of the Atmosphere
• Earth’s early atmosphere contained mostly hydrogen and helium
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The Evolution of the Atmosphere
• Earth’s early atmosphere contained mostly hydrogen and helium
• Two hypotheses exist that explain the dispersion of this early atmosphere
1) The gases escaped to space by overcoming gravity with large enough escape velocities
2) Collisions between earth and other large bodies launched the early atmosphere to space
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The Evolution of the Atmosphere
• Earth’s early atmosphere contained mostly hydrogen and helium
• Two hypotheses exist that explain the dispersion of this early atmosphere
1) The gases escaped to space by overcoming gravity with large enough escape velocities
2) Collisions between earth and other large bodies launched the early atmosphere to space
• A modern atmosphere began to form through outgassing by volcanic eruptions, and possibly through collisions of comets with earth (Both supplying mostly carbon dioxide and water vapor)
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The Evolution of the Atmosphere
• Water vapor condensed and precipitated to form oceans
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The Evolution of the Atmosphere
• Water vapor condensed and precipitated to form oceans
• Carbon dioxide lost to oceans
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The Evolution of the Atmosphere
• Water vapor condensed and precipitated to form oceans
• Carbon dioxide lost to oceans
• Oxygen released first through primitive oceanic bacteria, later through plants (protected by ozone layer)
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The Evolution of the Atmosphere
• Water vapor condensed and precipitated to form oceans
• Carbon dioxide lost to oceans
• Oxygen released first through primitive oceanic bacteria, later through plants (protected by ozone layer)
• Plants further reduced carbon dioxide
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The Evolution of the Atmosphere
• Water vapor condensed and precipitated to form oceans
• Carbon dioxide lost to oceans• Oxygen released first through primitive
oceanic bacteria, later through plants (protected by ozone layer)
• Plants further reduced carbon dioxide• Nitrogen slowly increased over long periods
of time through outgassing
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Composition of the Modern Atmosphere
• The atmosphere today contains:• Gases (permanent and variable)• Water droplets (clouds and precipitation)• Microscopic solid particles (aerosols)
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The Permanent Gases• Permanent gases form a constant proportion of
the atmosphere, and have long residence times (thousands to millions of years)
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The Variable Gases
• Variable gases vary in atmospheric concentration in both time and space
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Water Vapor
• Water vapor (H2O) – Extremely important variable gas with short residence time (~10 days)
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Water Vapor
• Water vapor (H2O) – Extremely important variable gas with short residence time (~10 days)
• Water vapor is the invisible gaseous phase of water (you can only see liquid water droplets!)
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Water Vapor
• Water vapor (H2O) – Extremely important variable gas with short residence time (~10 days)
• Water vapor is the invisible gaseous phase of water (you can only see liquid water droplets!)
• Atmospheric concentration highest near ocean surface in tropics (~4%)
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Water Vapor
• Water vapor (H2O) – Extremely important variable gas with short residence time (~10 days)
• Water vapor is the invisible gaseous phase of water (you can only see liquid water droplets!)
• Atmospheric concentration highest near ocean surface in tropics (~4%)
• Atmospheric concentration lowest in deserts and at high altitudes (near 0%)
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The Hydrologic Cycle
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Water Vapor Satellite Imagery
• Satellite imagery reveals variable nature of water vapor concentration
• Water vapor satellite imagery also reveals moist and dry regions of the atmosphere (visible imagery does not)
Water vapor imagery Visible imagery
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Carbon Dioxide
• Carbon dioxide (CO2) – An important greenhouse gas with concentration 0.0386% (386 ppm) and residence time of 150 years
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Carbon Dioxide
• Carbon dioxide (CO2) – An important greenhouse gas with concentration 0.0386% (386 ppm) and residence time of 150 years
• Sources - 1) Plant and animal respiration
2) Volcanoes
3) Organic decay
4) Combustion
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Carbon Dioxide
• Carbon dioxide (CO2) – An important greenhouse gas with concentration 0.0386% (386 ppm) and residence time of 150 years
• Sources - 1) Plant and animal respiration
2) Volcanoes
3) Organic decay
4) Combustion
• Sinks - 1) Photosynthesis (plants)
2) The oceans
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Carbon Dioxide• Seasonal oscillation in concentration• Long term increase in concentration (due to
anthropogenic combustion and deforestation)
Mauna Loa Observatory (~11,000 ft. in Hawaii)
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Ozone
• Ozone (O3) – A beneficial and harmful variable gas
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Ozone
• Ozone (O3) – A beneficial and harmful variable gas
• O3 concentrations in the stratosphere (~10-30 miles above sea level) are relatively high (15 ppm), occurs from natural chemical reactions
Absorbs UV radiation!!
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Ozone
• Ozone (O3) – A beneficial and harmful variable gas
• O3 concentrations in the stratosphere (~10-30 miles above sea level) are relatively high (15 ppm), occurs from natural chemical reactions
Absorbs UV radiation!!
• O3 concentration near earth’s surface is usually near zero, but can increase to 0.15 ppm through chemical reactions in polluted air
Irritant!!
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Stratospheric Ozone Creation and Destruction
• Natural ozone cycleO2 + uv --> O + O
O2 + O --> O3
O3 + uv --> O + O2
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Stratospheric Ozone Creation and Destruction
• Natural ozone cycleO2 + uv --> O + O
O2 + O --> O3
O3 + uv --> O + O2
• After introduction of CFCs
CFC + uv --> Cl + CFCbyproduct
Cl + O3 --> ClO + O2
O + ClO --> Cl + O2
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Global CFCs
A global success story!
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Methane
• Methane (CH4) – A variable gas with residence time ~10 years that has high potential for greenhouse warming
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Methane
• Methane (CH4) – A variable gas with residence time ~10 years that has high potential for greenhouse warming
• Sources - 1) Rice cultivation, wetlands
2) Mining
3) Biomass burning
4) Fossil fuel extraction
5) Animal digestion
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Methane
• Methane (CH4) – A variable gas with residence time ~10 years that has high potential for greenhouse warming
• Sources - 1) Rice cultivation, wetlands
2) Mining
3) Biomass burning
4) Fossil fuel extraction
5) Animal digestion
• Sinks - 1) Atmospheric chemical reactions
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Methane
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Aerosols
• Aerosols – Small solid particles (e.g. dust, smoke, sea spray, volcanic ash)
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Aerosols
• Aerosols – Small solid particles (e.g. dust, smoke, sea spray, volcanic ash)
• Typical concentration = 17,000/in3
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Aerosols
• Aerosols – Small solid particles (e.g. dust, smoke, sea spray, volcanic ash)
• Typical concentration = 17,000/in3
• Typical diameter = 10 microns (0.00001 meter)
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Aerosols
• Aerosols – Small solid particles (e.g. dust, smoke, sea spray, volcanic ash)
• Typical concentration = 17,000/in3
• Typical diameter = 10 microns (0.00001 meter)
• Typical life span = days to weeks
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Aerosols
• Aerosols – Small solid particles (e.g. dust, smoke, sea spray, volcanic ash)
• Typical concentration = 17,000/in3
• Typical diameter = 10 microns (0.00001 meter)
• Typical life span = days to weeks
• Mostly from natural sources
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Aerosols
• Aerosols – Small solid particles (e.g. dust, smoke, sea spray, volcanic ash)
• Typical concentration = 17,000/in3
• Typical diameter = 10 microns (0.00001 meter)
• Typical life span = days to weeks
• Mostly from natural sources
• Primary sinks include dry and wet deposition
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Aerosols
• Aerosols – Small solid particles (e.g. dust, smoke, sea spray, volcanic ash)
• Typical concentration = 17,000/in3
• Typical diameter = 10 microns (0.00001 meter)• Typical life span = days to weeks• Mostly from natural sources• Primary sinks include dry and wet deposition• Act as cloud condensation nuclei (without
aerosols, there would never be clouds)
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Aerosols
Lubbock Dust Storm
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Aerosols
Forest fire smoke in CA
Haboob in Phoenix, AZ
Eruption of Mount St. Helens
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Vertical Structure of the Atmosphere
• There are various ways to characterize the vertical nature of the atmosphere
• Density profile• Temperature profile (Most common)• Chemical profile• Electrical profile
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The Chemical Profile
• Homosphere – The atmosphere below 80km (~50miles)
• Permanent gases are in constant concentration• Generally “atmosphere” refers to the homosphere
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The Chemical Profile
• Homosphere – The atmosphere below 80km (~50miles)
• Permanent gases are in constant concentration• Generally “atmosphere” refers to the homosphere
• Heterosphere – Above the homosphere• Lighter gases dominate (helium, hydrogen)• No permanent gases
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The Density Profile
• Density is defined as the amount of mass per unit volume
Density of various materials
1) Water 1000 kg/m3
2) Steel 7800 kg/m3
3) Air (at sea level) 1.2 kg/m3
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The Density Profile
• The atmosphere is compressible
• Density decreases with height
Sea level
Top of atmosphere
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Atmospheric Pressure
• Pressure = Force per unit area
• Pressure in a free fluid is related to the weight of fluid above
• For example, the pressure on your ears increases at the same rate as you dive deeper in a pool
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Atmospheric Pressure
• How does pressure decrease with height in the atmosphere?
Sea level
Top of atmosphere
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Atmospheric Pressure
• How does pressure decrease with height in the atmosphere?
• Pressure decreases with height fastest near the surface, less so aloft
Sea level
Top of atmosphere
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Atmospheric Pressure Profile
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Atmospheric Pressure
• How much pressure (psi) is pushing on you right now?
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Atmospheric Pressure
• How much pressure (psi) is pushing on you right now?
• Average sea-level pressure = 14.7 psi
= 1013.25 mb
= 101325 Pa
= 29.92 in Hg
= 1 atmosphere
Record high sea-level pressure = 1083.8 mb (Siberia, 1968)
Record low sea-level pressure = 870 mb (Typhoon Tip near Guam, 1979)
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Atmospheric Pressure
• What about the upside-down cup of water…
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Atmospheric Pressure
• What about the upside-down cup of water…
Other interesting realizations of atmospheric pressure
Suction cups
Lungs
Vacuum cleaner
1 more pressure experiment to come…
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Layering the Atmosphere Based on Temperature
• 4 layers identified by similar temperature rates of change with height
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A Quick Note on Temperature…
• Temperature is expressed in Fahrenheit (oF), Celsius (oC), or Kelvin (K)
Conversions
K = oC +273.16
oF = 9/5 * oC + 32
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Troposphere
• Troposphere – Lowest atmospheric layer
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Troposphere
• Troposphere – Lowest atmospheric layer• Located at about 0-11km (0-7.0 mi)
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Troposphere
• Troposphere – Lowest atmospheric layer• Located at about 0-11km (0-7.0 mi)• Practically all weather occurs in the
troposphere
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Troposphere
• Troposphere – Lowest atmospheric layer• Located at about 0-11km (0-7.0 mi)• Practically all weather occurs in the
troposphere• Temperature generally decreases with
height (environmental lapse rate, typical value = 6.5oC/km) – Why??
![Page 70: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/70.jpg)
Troposphere
• Troposphere – Lowest atmospheric layer• Located at about 0-11km (0-7.0 mi)• Practically all weather occurs in the
troposphere• Temperature generally decreases with
height (environmental lapse rate, typical value = 6.5oC/km) – Why??
• Top of troposphere is called the tropopause
![Page 71: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/71.jpg)
Troposphere
• Troposphere – Lowest atmospheric layer• Located at about 0-11km (0-7.0 mi)• Practically all weather occurs in the
troposphere• Temperature generally decreases with height
(environmental lapse rate, typical value = 6.5oC/km) – Why??
• Top of troposphere is called the tropopause• Contains 80% of atmospheric mass
![Page 72: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/72.jpg)
Troposphere
• Troposphere – Lowest atmospheric layer• Depth varies with latitude and season
![Page 73: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/73.jpg)
Stratosphere
• Stratosphere – The atmospheric layer above the troposphere (2nd layer up)
![Page 74: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/74.jpg)
Stratosphere
• Stratosphere – The atmospheric layer above the troposphere (2nd layer up)
• Only weather in stratosphere are overshooting thunderstorm tops
![Page 75: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/75.jpg)
Stratosphere
• Stratosphere – The atmospheric layer above the troposphere (2nd layer up)
• Ozone layer is located in stratosphere
![Page 76: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/76.jpg)
Stratosphere
• Stratosphere – The atmospheric layer above the troposphere (2nd layer up)
• Ozone layer is located in stratosphere• Temperature increases with height
(inversion) – due to O3 absorbtion of UV
![Page 77: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/77.jpg)
Stratosphere
• Stratosphere – The atmospheric layer above the troposphere (2nd layer up)
• Ozone layer is located in stratosphere• Temperature increases with height
(inversion) – due to O3 absorbtion of UV
• Located from about 11-50 km
![Page 78: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/78.jpg)
Stratosphere
• Stratosphere – The atmospheric layer above the troposphere (2nd layer up)
• Ozone layer is located in stratosphere• Temperature increases with height
(inversion) – due to O3 absorbtion of UV
• Located from about 11-50 km• Top of stratosphere is called the
stratopause
![Page 79: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/79.jpg)
Stratosphere
• Stratosphere – The atmospheric layer above the troposphere (2nd layer up)
• Ozone layer is located in stratosphere• Temperature increases with height
(inversion) – due to O3 absorbtion of UV
• Located from about 11-50 km• Top of stratosphere is called the
stratopause• Contains about 19.9% of atmospheric mass
![Page 80: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/80.jpg)
Mesosphere and Thermosphere
• The mesosphere (3rd layer up) and the thermosphere (4th layer up) contain only 0.1% of atmospheric mass
![Page 81: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/81.jpg)
Mesosphere and Thermosphere
• The mesosphere (3rd layer up) and the thermosphere (4th layer up) contain only 0.1% of atmospheric mass
• Mesosphere located from about 50-80km• Temperature decreases with height in the
mesosphere• Thermosphere located above 80km• Temperature increases with height in the
thermosphere
![Page 82: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/82.jpg)
Characterizing the Atmosphere Based on Electrical Properties
• The ionosphere is an atmospheric layer located from the upper mesosphere into the thermosphere
![Page 83: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/83.jpg)
Characterizing the Atmosphere Based on Electrical Properties
• The ionosphere is an atmospheric layer located from the upper mesosphere into the thermosphere
• The ionosphere contains electrically charged particles called ions due to UV radiation
![Page 84: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/84.jpg)
Characterizing the Atmosphere Based on Electrical Properties
• The ionosphere is an atmospheric layer located from the upper mesosphere into the thermosphere
• The ionosphere contains electrically charged particles called ions due to UV radiation
• The ionosphere affects AM radio waves, absorbing them in the day and reflecting them at night
![Page 85: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/85.jpg)
Characterizing the Atmosphere Based on Electrical Properties
• The ionosphere is an atmospheric layer located from the upper mesosphere into the thermosphere
• The ionosphere contains electrically charged particles called ions due to UV radiation
• The ionosphere affects AM radio waves, absorbing them in the day and reflecting them at night
• The ionosphere creates the northern lights (aurora borealis) and the southern lights (aurora australis) through interactions between the sun’s rays and earth’s magnetic field
![Page 86: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/86.jpg)
The Ionosphere
![Page 87: Chapter 1 – The Composition and Structure of the Atmosphere.](https://reader031.fdocuments.us/reader031/viewer/2022012913/56649e425503460f94b3475e/html5/thumbnails/87.jpg)
The Ionosphere
The Northern LightsPhoto from climate.gi.alaska.edu/Curtis