© 2017 Pearson Education, Inc. Heating the Atmosphere Chapter 11 Lecture Natalie Bursztyn Utah State University Foundations of Earth Science Eighth Edition
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Heating the
Atmosphere
Chapter 11 Lecture
Natalie Bursztyn
Utah State University
Foundations of
Earth ScienceEighth Edition
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• Distinguish between weather and climate.
• Name the basic elements of weather and climate.
Focus Questions 11.1
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• Weather
– Occurs over a short period of time
– Constantly changing
• Climate
– Averaged over a long period of time
– Generalized, composite of weather
Focus on the Atmosphere
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• Elements of weather and climate
– Properties that are measured regularly:
• Air temperature
• Humidity
• Type and amount of cloudiness
• Type and amount of precipitation
• Air pressure
• Wind speed and direction
Weather and Climate
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Weather and Climate
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• List the major gases composing Earth’s
atmosphere.
• Identify the components that are most important
to understanding weather and climate.
Focus Questions 11.2
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• Air is a mixture of discrete gases
• Major components of clean, dry air
– 78% Nitrogen (N)
– 21% Oxygen (O2)
– Argon and other gases
– 0.04% Carbon dioxide (CO2)
Composition of the Atmosphere
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Major Components
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• Water vapor
– Up to 4% of air’s volume
– Forms clouds and precipitation
– Greenhouse gas
• Aerosols
– Tiny solid and liquid particles
– Water vapor can condense on solids
– Reflect sunlight
– Color sunrise and sunset
Variable Components
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Variable Components
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• Ozone
– Three atoms of oxygen (O3)
– Distribution not uniform
– Concentrated between 10 and 50 km above the surface
– Absorbs harmful UV radiation
Variable Components
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• Interpret a graph that shows changes in air
pressure from Earth’s surface to the top of the
atmosphere.
• Sketch and label a graph that shows atmospheric
levels based on temperature.
Focus Questions 11.3
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• Atmospheric pressure is the weight of the air
above.
– Average sea level pressure is 1000 millibars or 14.7 psi
– Pressure decreases with altitude
• Half of atmosphere is below 3.5 mi (5.6 km)
• 90% of atmosphere is below 10 mi (16 km)
Pressure Changes
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Pressure Changes
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• Four atmospheric layers based on temperature
– Troposphere
• Lowermost layer
• Temperature decreases with increasing altitude
• Environmental lapse rate
– Average 6.5C per km or 3.5F per 1000 feet
• Thickness varies
– Average height is about 12 km
• Outer boundary is the tropopause
Temperature Changes
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Temperature Changes
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• The environmental lapse rate is variable
– Actual environmental lapse rate for any particular time
and place
– Measured with a radiosonde
– Attached to a balloon and transmits data by radio
Temperature Changes
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Temperature Changes
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• Stratosphere
– 12 to 50 km
– Temperature increases at top
– Outer boundary is the stratopause
• Mesosphere
– 50 to 80 km
– Temperature decreases
– Outer boundary is the mesopause
• Thermosphere
– No well-defined upper limit
– Fraction of atmosphere’s mass
– Gases moving at high speeds
Temperature Changes
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Temperature Changes
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• Explain what causes the Sun angle and length of
daylight to change during the year.
• Describe how these changes produce the
seasons.
Focus Questions 11.4
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• Earth’s motions
– Rotation on its axis
• Once every 24 hours
• Circle of illumination is the line separating Earth’s
lighted half from dark half
– Orbital motion around the Sun
• Seasons
– Result of:
• Changing Sun angle
• Changing length of daylight
Earth–Sun Relationships
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Earth–Sun Relationships
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• Seasons
– Caused by Earth’s changing orientation to the Sun
• Axis is inclined 23.5º
• Axis is always pointed in the same direction
Earth–Sun Relationships
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• Special days (Northern Hemisphere)
– Summer solstice: June 21–22
• Sun’s vertical rays located at Tropic of Cancer
• 23.5º N latitude
– Winter solstice: December 21–22
• Sun’s vertical rays located at Tropic of Capricorn
• 23.5º S latitude
– Autumnal equinox: September 22–23
• Sun’s vertical rays located at equator (0º latitude)
– Spring equinox: March 21–22
• Sun’s vertical rays located at equator (0º latitude)
Earth–Sun Relationships
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Earth–Sun Relationships
[insert Figure 11.15 and Table 11.1 here]
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Earth–Sun Relationships
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• Distinguish between heat and temperature.
• List and describe the three mechanisms of heat
temperature.
Focus Questions 11.5
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• Heat is synonymous with thermal energy
• Temperature refers to the intensity, or degree of
"hotness"
• Heat is always transferred from warmer to cooler
objects
Energy, Heat, and Temperature
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• Mechanisms of heat transfer
– Conduction
• Molecular activity
– Convection
• Mass movement within a substance
– Radiation (electromagnetic radiation)
• Gamma waves, X-rays
• Ultraviolet,visible, infrared
• Microwaves and radio waves
Energy, Heat, and Temperature
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Energy, Heat, and Temperature
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• Laws of Radiation
– All objects emit radiant energy
– Hotter objects radiate more total energy per unit
area than colder objects
– Hotter objects radiate more short-wavelength radiation
than cooler objects
– Good absorbers of radiation are good emitters as well
Energy, Heat, and Temperature
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Energy, Heat, and Temperature
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• Sketch and label a diagram that shows the paths
taken by incoming solar radiation.
• Summarize the greenhouse effect.
Focus Questions 11.6
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• Incoming solar radiation
– Atmosphere is largely transparent to incoming solar
radiation
– Atmospheric effects
• Reflection
– Albedo (percent reflected)
• Scattering
• Absorption
– Most visible radiation reaches the surface
– About 50% absorbed at Earth’s surface
Heating the Atmosphere
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Heating the Atmosphere
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Heating the Atmosphere
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Heating the Atmosphere
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• Radiation from Earth’s surface
– Earth re-radiates longer wavelengths
– Terrestrial radiation
– Terrestrial radiation is absorbed by
• Carbon dioxide and water vapor
• Lower atmosphere is heated from Earth’s surface
– Heating of the atmosphere is termed the greenhouse
effect
Heating the Atmosphere
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Heating the Atmosphere
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• Summarize the nature and cause of the
atmosphere’s changing composition since
around 1750.
• Describe the atmosphere’s response and some
possible future consequences.
Focus Questions 11.7
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• CO2 levels are rising
– Industrialization of the past 200 years
– Burning fossil fuels
• coal, natural gas, and petroleum
– Deforestation
• Present CO2 level is 30% higher than its highest
level over at least the past 800,000 years
Human Impact on Global Climate
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Human Impact on Global Climate
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Human Impact on Global Climate
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• Important impacts of human-induced global
warming:
– Rise in sea level
– Shift in large-storm paths
• Changes in precipitation distribution
• Changes in occurrence of severe weather
– Stronger tropical storms
– Increasing frequency and intensity of heat waves and
droughts
• Gradual environmental shifts
Human Impact on Global Climate
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Human Impact on Global Climate
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• Calculate five commonly used types of
temperature data.
• Interpret a map that depicts temperature data
using isotherms.
Focus Questions 11.8
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For the Record: Air Temperature Data
• Temperature measurement
– Daily maximum and minimum
– Other measurements
• Daily mean temperature
• Daily range
• Monthly mean
• Annual mean
• Annual temperature range
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• Isotherms used to examine distribution of air
temperatures over large areas
– Line that connects points of the same temperature
– iso = equal, therm = temperature
– Easy to visualize temperature gradient
For the Record: Air Temperature Data
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For the Record: Air Temperature Data
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• Discuss the principal controls of temperature.
• Use examples to describe their effects.
Focus Questions 11.9
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• Temperature control – any factor that causes
temperature to vary from place to place and from
time to time
– Receipt of solar radiation
– Differential heating of land and water
• Land heats more rapidly than water
• Land gets hotter than water
• Land cools faster than water
• Land gets cooler than water
Why Temperatures Vary: The Controls
of Temperature
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• Specific heat is the
amount of energy
needed to raise the
temperature of 1 gram
of a substance
1 degree Celsius
Why Temperatures Vary: The Controls
of Temperature
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Why Temperatures Vary: The Controls
of Temperature
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• Other important controls
– Altitude
– Geographic position
– Cloud cover
– Albedo
Why Temperatures Vary: The Controls
of Temperature
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Why Temperatures Vary: The Controls
of Temperature
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• Interpret the patterns depicted on world maps of January and July temperatures.
Focus Question 11.10
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• Temperature maps
– Temperatures are adjusted to sea level
– January and July used for analysis
• Represent temperature extremes
World Distribution of Temperature
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• Global temperature patterns
– Temperature decreases poleward from tropics
– Isotherms exhibit latitudinal shift with seasons
– Warmest and coldest over land
World Distribution of Temperature
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World Distribution of Temperature
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World Distribution of Temperature
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• Global temperature patterns
– Southern Hemisphere
• Isotherms are straighter
• Isotherms are more stable
– Isotherms show ocean currents
– Annual temperature range
• Small near equator
• Increases with an increase in latitude
• Greatest over continental locations
World Distribution of Temperature