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4.8: Review and Additional Online Resources

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    Review

    Aurora Australis
    Figure \(\PageIndex{1}\)

    Assess your learning. Start with the "Important Terms and Concepts" to ensure you know the terminology related to the topic of the chapter and concepts discussed. Move on to the "Review Questions" to answer critical thinking questions about concepts and processes discussed in the chapter. Finally, test your overall understanding by taking the "Self-assessment quiz".

    Important Terms and Concepts \(\PageIndex{1}\)
    • Energy
      the ability to do work on matter
    • Potential Energy
      the energy of position
    • Kinetic Energy
      the energy of motion
    • Heat
      aka thermal energy; the total energy associated with random atomic and molecular motions of a substance
    • Calorie
      a unit of measurement for heat. A calorie is the amount of heat required to raise the temperature of one gram of water through 1oC.
    • Specific Heat
      the heat required to raise the temperature of one unit substance (e.g., gram) through a particular temperature interval.
    • Joule
      unit of measurement for energy. One joule is the equivalent of one watt of power radiated or dissipated for one second.
    • Conduction
      the transfer of heat from warmer to colder portions of the mass in a solid
    • Convection
      heat is transferred by the circulation of molecules in fluids
    • Radiation
      the transfer of energy via electromagnetic waves.
    • Advection
      a term that is applied to the horizontal transfer of heat by the wind
    • Temperature
      a measure of the average kinetic energy level of a substance, the degree of hotness or coldness
    • Amplitude
      the height of the wave
    • Wavelength
      the distance between successive crests
    • Photon
      a bundle of energy
    • selective absorber
      absorbs only particular wavelengths of light
    • Shortwave radiation
      ultraviolet, visible, and a portion of infrared energy
    • Longwave radiation
      infrared, (like microwave, TV, radio waves)
    • Direct shortwave radiation
      shortwave radiation able to penetrate through the atmosphere without having been affected by constituents of the atmosphere in any way.
    • Diffuse Shortwave radiation
      shortwave radiation that has been scattered by gases in the atmosphere
    • Insolation
      the total incoming solar radiation
    • Albedo
      The proportion of light reflected from a surface
    • Net shortwave radiation
      the difference between incoming and outgoing shortwave radiation. K= (S+D) - (S+D)a
    • Terrestrial longwave radiation
      The energy absorbed by the surface is radiated from the Earth
    • Atmospheric counter-radiation
      long-wave radiation emitted from the earth to the atmosphere after it has absorbed the shorter-wave radiation of the sun.
      • Net radiation
        the difference between incoming (i.e., S and L↓) and outgoing components of radiation (S+D)a and L↑: Q*= [(S+D) - (S+D)a] + L↓ - L↑
    • Sensible heat transfer
      heat energy transferred between the surface and air when there is a difference in temperature between them
    • Latent heat transfer
      transfer of energy where temperature does not change/cannot be sensed
    • Ground heat transfer
      The transfer of energy to and from the surface
    Review Questions \(\PageIndex{1}\)

    Generally speaking, where is the highest and lowest amounts of insolation and net radiation on a global basis?

    Answer

    Insolation: highest amount in the tropical/subtropical deserts; minimum at the poles. Net radiation: maximum in the tropical/subtropical oceans; minimum at the poles.

    What is albedo and what determines the albedo of a surface?

    Answer

    Albedo is the proportion of light reflected from the surface. It is mostly determined by the color of the surface though sun angle influences albedo for some surfaces like water.

    What determines the amount of radiation emitted by a body?

    Answer

    The amount of radiation emitted by a body depends on the temperature of the emitting body.

    What determines sun angle at a place?

    Answer

    Sun angle is a largely determined by the tilt of Earth's axis. The sun angle varies by latitude, time of day. time of year, and slope of the surface.

    Why do physical geographers refer to the gasses of the atmosphere as a "selective absorber" of radiation?

    Answer

    A gas that is a selective absorber is one that absorbs only particular wavelengths of light. The gasses of Earth's atmosphere are considered selective absorbers as they tend to allow shortwave solar radiation through but absorbs longwave radiation emitted by the surface.

    Compare and contrast conduction, convection, and radiation.

    Answer

    Conduction is the heat transfer via molecular collisions. Convection is heat transfer by circulation. Radiation is heat transfer via electromagnetic radiation.

    Explain why the maximum wavelength of emission for the Sun is different than that of the Earth.

    Answer

    The maximum wavelength of emission depends on the temperature of the emitting body, the hotter the body the shorter the maximum wavelength of emission. The Sun being much warmer than the Earth emits most of its energy in the shortwave end of the electromagnetic spectrum while the Earth emits its energy in the longwave end of the electromagnetic spectrum.

    Briefly describe how the vertical rays of the sun at noon change throughout the year.

    Answer
    • March 21 and Sept 23: 0o latitude
    • June 22: 23.5o North latitude
    • Dec 22: 23.5o degrees South latitude

    How do clouds affect solar radiation?

    Answer

    They block incoming solar radiation reflecting it of their top and back out to space. They diffuse incoming solar radiation as well.

    What is net radiation?

    Answer

    Net radiation is an accounting of incoming and outgoing components of radiation. It also is the amount of energy used to do work in the earth system.

    Briefly describe the latitudinal variation of the radiation balance.

    Answer

    There is a net gain of radiation between about 38o North and South latitude. Poleward of these latitudes there is a net loss of radiation.

    Compare and contrast latent heat transfer in humid and arid regions.

    Answer

    There is more latent heat flux in a humid region because there is more water available than in a desert region.

    Exercise \(\PageIndex{1}\)
    1. The earth is closest to the sun on about
      1. January 4th
      2. March 21st
      3. July 4th
      4. June 21st
    2. Latent heat is transferred into the air by
      1. conduction
      2. convection
      3. radiation
      4. none of the above
    3. Which place likely receives the most insolation at noon (barring any effect of clouds)?
      1. 90 N on June 22nd
      2. 45 N on June 22nd
      3. 23.5 N on June 22nd
      4. 0 on June 22nd
    4. The highest amount of net radiation is found
      1. over polar seas
      2. over midlatitude continents
      3. over subtropical deserts
      4. over tropical oceans
    5. The earth's maximum wavelength of emission is about
      1. .5 micrometers
      2. 1.0 micrometers
      3. 10 micrometers
      4. 100 micrometers
    6. The sun is directly overhead of 23.5 S at noon on
      1. March 21st
      2. June 22nd
      3. Sept. 23rd
      4. Dec. 22
    7. The hotter the emitting body
      1. the shorter the wavelength of maximum emission
      2. the longer the wavelength of maximum emission
      3. the less energy it will emit
      4. the more latent heat it will store
    8. Clouds are good absorbers of radiation at a wavelength of about
      1. .5 micrometers
      2. 1 micrometers
      3. 10 micrometers
      4. at all the above wavelengths
    9. ________ is the total energy associated with random atomic and molecular motions of a substance.
      1. radiation
      2. temperature
      3. potential energy
      4. heat
    10. Where would I expect to find the largest amount of latent heat transfer into the air?
      1. The west coast of the United States near Los Angeles
      2. The east coast of the United States near New York
      3. In the middle of the Sonoran Desert of Mexico
      4. In the tropical rain forest of Brazil

    Answer

    1. A
    2. B
    3. C
    4. D
    5. C
    6. D
    7. A
    8. C
    9. D
    10. B

    Additional Resources

    Focus on The Physical Environment: "Arbiters of Energy" (NASA Earth Observatory)

    World of Change: Solar Activity

    Multimedia

    Particles and Waves (Annenberg/CPB:) The Mechanical Universe "Evidence that light can sometimes act like a particle leads to quantum mechanics, the new physics." Go to The Mechanical Universe site and scroll to "Particles and Waves". One-time free registration may be required.

    This page titled 4.8: Review and Additional Online Resources is shared under a CC BY-SA 4.0 license and was authored, remixed, and/or curated by Michael E. Ritter (The Physical Environment) via source content that was edited to the style and standards of the LibreTexts platform.