Chapter 18: Energy Balance in the Atmosphere

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Chapter 18 Energy Balance in the Atmosphere
Fig. 18-CO, p.428
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Incoming Solar Radiation

• Almost all surface events are driven by solar
  energy.
• Weather state of the atmosphere at a given place
  and time
• Climate characteristic weather of a region
  (particularly temp and precipitation) averaged
  over several decades.
• Earth receives one two-billionth of the total
  solar output! Light behaves as a particle
  (Newton) and wave (Hooke and Huygens) at the same
  time. Photons travel at the speed of light
  (through the vacuum of space at 300,000 km/sec)
  from Sun to Earth (150 million km) in how many
  minutes?

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• Visible light is a tiny portion of the
  electromagnetic spectrum. The terms used to
  describe a light wave are identical to those used
  for water, sound and other types of waves.

Fig. 18-1, p.429
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Fig. 18-2, p.430
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• Absorption and Emission
• Absorption of a photon causes suntan or sunburn
  (for example).
• Emission occurs when the photon hooks up with an
  electron and falls to a lower energy state. An
  iron bar (at room temp) emits infrared radiation.
  If heated it emits red progressing to white
  temp of source determines wavelength and color
  emitted.
• The Sun (very hot) emits high-energy (low
  wavelength) radiationrocks and soil re-emit it
  as low-energy (invisible) infrared radiation.

Fig. 18-3, p.431
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• Albedo the proportional reflectance of a
  surface. The albedo of common Earth surfaces
  vary greatly.
• What would happen to the surface of our planet if
  glaciers and cloud cover grew?

Fig. 18-4, p.431
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• Scattering inversely proportional to the
  wavelength of light. Short wavelength (blue
  light) scatters more than long wavelength (red
  light). So, sky is blueSun is yellow because
  this is color of white light with most of the
  blue light removedwhat color would the Sun be if
  viewed above our atmosphere?

Fig. 18-5, p.432
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• The Radiation Balance one-half of the incoming
  solar radiation reaches the Earths surface. The
  atmosphere scatters, reflects and absorbs the
  other half. All of the radiation absorbed by the
  Earths surface is re-radiated as long-wavelength
  heat radiation.

Fig. 18-6, p.432
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• Greenhouse Effect 1. rocks, soil and water
  absorb short-wavelength solar radiation and
  become warmer. 2. the Earth re-radiates the
  energy as long-wavelength infrared heat rays. 3.
  molecules in the atmosphere absorb some of the
  heat, and the atmosphere becomes warmer. What
  are the main greenhouse gases?

Fig. 18-7, p.433
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Energy Storage and Transfer the driving
mechanisms for weather and climate

• Heat and Temperature temperature is proportional
  to the avg. speed of atoms or molecules in a
  sample (cup of boiling water and bathtub full of
  ice water)heat is total energy in a sample (many
  more molecules, so total heat energy is greater).

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• Heat transport by conduction and convection (and
  advection).

Fig. 18-8, p.434
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Fig. 18-8a, p.434
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Fig. 18-8b, p.434
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• Changes of State at Earths surface, water
  commonly exists in all three states (ice, liquid
  and water vapor)Latent heat (stored heat) is the
  energy released or absorbed when a substance
  changes from one state to another.

Fig. 18-9, p.435
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Heat Storage

• Place a pan of water and a rock outside on a hot
  summer day, which becomes hotter and why?
• Specific Heat amount of energy needed to raise
  the temperature of 1 gram of material by 1 degree
  C. Water has very high specific heatwhat are
  the implications?
• Why are coastal areas are cooler in the summer
  and warmer in the winter than continental
  interiors.

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• Temperature changes with latitude and season
  Before seasons, do you understandLatitude and
  Longitude(see Focus On, page 459)
• How to locate a place on Earth.
• Earth has natural points of reference (the North
  and South geographic poles lie on Earths spin
  axis).
• Lines of Latitude form imaginary horizontal
  rings around the spin axis. Equator at 0 degrees
  latitude. What about North and South Poles?
• Lines of Longitude also in degrees, beginning at
  Greenwich, England (arbitrarily chosen, 0 degrees
  longitude).

p.436
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• If light shines directly overhead, the radiation
  is concentrated on a small area. However, if the
  light shines at an angle, or if the surface is
  tilted, the radiant energy is dispersed over a
  larger area. How does this apply to the Equator
  and Polar regions of the Earth?

Fig. 18-10, p.437
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• Where does the most intense solar radiation
  strike Earth?
• Equator receives the most concen-trated solar
  radiation
• Temps cooler toward poles

Fig. 18-11, p.437
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• Weather changes with the seasons because the
  Earths axis is tilted relative to the plane of
  its orbit around the Sun. The Northern
  Hemisphere receives more direct sunlight during
  summer, but less during winter. Tilt is 23.5
  degrees tropic of Cancer (23.5 degrees north
  latitude) tropic of Capricorn (23.5 degrees
  south latitude).

Fig. 18-12, p.438
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• Canadian Arctic, midnight during Julylocation is
  70 degrees north latitude (Beaufort Sea).

Fig. 18-13, p.438
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• During equinoxes (equal nights) all areas on the
  Earth receive about 12 hours of daylight and
  darkness. Poles not tilted toward or away from
  the Sun.
• In fact, all areas of the Earth receive the same
  total number of hours of sunlight every year, so
  why is there such a variation in climates?

Table 18-1, p.439
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• Temperature changes with geography. Lines of
  avg. temperature (isotherms) show global
  temperature distributions in January and July.
• Changes with altitude.

Fig. 18-14, p.440
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Fig. 18-14a, p.440
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Fig. 18-14b, p.440
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• Ocean Effects continental St. Louis (red line)
  is colder in the winter and warmer in the summer
  than coastal San Francisco.

Fig. 18-15, p.441
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• Paris is warmed by the Gulf Stream and the North
  Atlantic Drift. St. Johns is alternately warmed
  by the Gulf Stream and cooled by the Labrador
  Current. This cooling effect depresses the
  temperature of St. Johns year round.

Fig. 18-16, p.441
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• Wind Direction during the summer, temperatures
  in Vladivostok and Portland are nearly the same.
  In the winter, cold Arctic winds cool Vladivostok
  to temps much lower than Portland.

Fig. 18-17, p.442
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• Cloud cover and Albedo. Clouds cool the Earths
  surface during the day, but warm is during the
  night.

Fig. 18-18, p.443
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p.444