Abstract

Our understanding of atmospheric scattering phenomena has increased through the combined developments of new electro-optical instrumentation, theoretical solutions for complex model atmospheres, and large computers enabling computation of such solutions. Earth satellites permit external, planetwide observations of our atmosphere, while spacecraft permit detailed measurements of the scattering by other planetary atmospheres. Some recent results are: elucidation of the effects of ozone absorption and high-altitude aerosol scattering on twilight colors and polarization; identification of a cloudbow on Venus and consequent deduction of the cloud particle shape, size distribution, and refractive index; and, the interpretation of Rayleigh scattering on Jupiter in terms of cloud-top topography.

© 1979 Optical Society of America

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  5. M. Minnaert, The Nature of Light and Colour in the Open Air (Dover, New York, 1954) (reprint).
  6. J. C. Johnson, Physical Meteorology (MIT, Cambridge, Mass. and Wiley, N.Y., 1954).
  7. K. Bullrich, “Scattered Radiation in the Atmosphere and the Natural Aerosol,” Adv. Geophys. 10, 99–260, 1964.
    [Crossref]
  8. G. V. Rozenberg, Twilight: A Study in Atmospheric Optics (Plenum, New York, 1966).
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  11. E. J. McCartney, Optics of the Atmosphere (Wiley, New York, 1976).
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    [Crossref]
  13. S. Chandrasekhar, Radiative Transfer (Dover, New York, 1960) (reprint).
  14. S. Chandrasekhar and D. D. Elbert, “The Illumination and Polarization of the Sunlit Sky on Rayleigh Scattering,” Trans. Am. Philos. Soc. 44, 643–728 (1954).
    [Crossref]
  15. G. W. Kattawar, G. N. Plass, and S. J. Hitzfelder, “Multiple scattered radiation emerging from Rayleigh and continental haze layers. 1: Radiance, polarization, and neutral points,” Appl. Opt. 15, 632–647 (1976).
    [Crossref] [PubMed]
  16. K. L. Coulson, “On the Solar Radiation Field in a Polluted Atmosphere,” J. Quant. Spectrosc. Radiat. Transfer 11, 739–755 (1971).
    [Crossref]
  17. F. Unz, “Die Konzentration des Aerosols in Troposphäre und Stratosphäre aus Messungen der Polarisation der Himmelsstrahlung im Zenit,” Beitr. Phys. Atmos. 42, 1–35 (1969).
  18. C. Darwin, Journal of Researches into the Natural History and Geology of the Countries Visited during the Voyage of the H.M.S. Beagle (Heritage, New York, 1957) (reprint edition).
  19. C. N. Adams, G. N. Plass, and G. W. Kattawar, “The Influence of Ozone and Aerosols on the Brightness and Color of the Twilight Sky,” J. Atmos. Sci. 31, 1662–1674 (1974).
    [Crossref]
  20. T. Gehrels, “Wavelength Dependence of the Polarization of the Sunlit Sky,” J. Opt. Soc. Amer. 52, 1164–1173 (1962).
    [Crossref]
  21. K. L. Coulson, “Atmospheric Turbidity Determinations by Skylight Measurements at the Mauna Loa Observatory,” Contributions in Atmospheric Science No. 13 (University of California, Davis, 1977).
  22. E. de Bary, K. Bullrich, and D. Lorenz, “Messungen der Himmelsstrahlung und deren Polarisationsgrad während der Sonnenfinsternis am 15.2.1961 in Viareggio (Italien),” Geofis. Pura Appl. 48, 193–198 (1961).
    [Crossref]
  23. D. L. Coffeen, J. Hämeen-Anttila, and R. H. Toubhans, “Airborne Infrared Polarimeter,” Space Sci. Instrum. 1, 161–175 (1975).
  24. J. E. Hansen and D. L. Coffeen, “Analysis of Cloud Polarization Measurements,” Proceedings of the Conference on Cloud Physics of the American Meteorological Society, edited by R. L. Lavoie and G. A. Dawson, 350–356 (1974).
  25. J. E. Hansen, “Multiple Scattering of Polarized Light in Planetary Atmospheres. Part II. Sunlight Reflected by Terrestrial Water Clouds,” J. Atmos. Sci. 28, 1400–1426 (1971).
    [Crossref]
  26. O. K. Garriott, “Visual Observations from Space,” Technical Digest of OSA Topical Meeting on Meteorological Optics, Keystone, Colorado, August, 1978 (unpublished).
  27. A. Dollfus, Thesis Univ. of Paris, 1955 (in English translation as NASA TT F-188, Washington, D.C., 1964).
  28. Preliminary data from C. Lillie (unpublished).
  29. Preliminary data by L. Travis, D. Coffeen, W. Lane, and J. Hansen, (unpublished).
  30. E. M. Shoemaker, J. J. Rennilson, and E. A. Whitaker, “Eclipse of Sun by Earth, as Seen from Surveyor III,” Surveyor Project Final Report, Part II. Science Results (NASA Technical Report 32-1265, Jet Propulsion Lab, Pasadena, 1968).
  31. A. Arking and J. Potter, “The Phase Curve of Venus and the Nature of its Clouds,” J. Atmos. Sci. 25, 617–628 (1968).
    [Crossref]
  32. A. Dollfus and D. L. Coffeen, “Polarization of Venus. I. Disk Observations,” Astron. Astrophys. 8, 251–266 (1970).
  33. D. L. Coffeen, “Wavelength Dependence of Polarization. XVI. Atmosphere of Venus,” Astron. J. 74, 446–460 (1969).
    [Crossref]
  34. J. E. Hansen and J. W. Hovenier, “Interpretation of the Polarization of Venus,” J. Atmos. Sci. 31, 1137–1160 (1974).
    [Crossref]
  35. See Figure 17 in D. L. Coffeen and J. E. Hansen, “Polarization Studies of Planetary Atmospheres,” in Planets, Stars and Nebulae Studied with Photopolarimetry, edited by T. Gehrels (University of Arizona, Tucson, 1974).
  36. It should be noted that the Venus particles form more of a“haze” than a “cloud.”K. Kawabata and J. E. Hansen [“Interpretation of the Variation of Polarization over the Disk of Venus, “ J. Atmos. Sci. 32, 1133–1139 (1975)] deduce a photon mean free path of ∼5 km at the level where the vertical cloud optical depth is unity, compared to a mean free path of ∼0.1 km in typical terrestrial clouds.
    [Crossref]
  37. L. D. Travis, D. L. Coffeen, J. E. Hansen, K. Kawabata, A. A. Lacis, W. A. Lane, S. S. Limaye, and P. H. Stone, “Orbiter Cloud Photopolarimeter Investigation,” Science 203, 781–785 (1979).
    [Crossref] [PubMed]
  38. P. Moore, The Planet Venus, 3rd ed. (Macmillan, New York, 1960).
  39. W. McD. Napier, “The Ashen Light on Venus,” Planet. Space Sci. 19, 1049–1051 (1971).
    [Crossref]
  40. M. V. Keldysh, “Venus Exploration with the Automatic Stations Venera 9 and Venera 10,” paper presented at the XIXth COSPAR Meeting, Philadelphia, Pa., 14–19 June, 1976, 43 pp. (unpublished);A. S. Selivanov, V. P. Chemodanov, M. K. Naraeva, A. S. Panfilov, M. A. Gerasimov, and I. I. Kobzeva, “A Television Experiment on the Surface of Venus,” translation of Kosm. Issled. 14, 674–677 (1976);A. S. Selivanov, A. S. Panfilov, M. K. Naraeva, V. P. Chemodanov, M. I. Bokhonov, and M. A. Gerasimov, “Photometric Analysis of Panoramas on the Surface of Venus,” translation of Kosm. Issled. 14, 678–686 (1976).
  41. A. J. Stratton, “Optical and Radio Refraction on Venus,” J. Atmos. Sci. 25, 666–667 (1968).
    [Crossref]
  42. R. O. Fimmel, W. Swindell, and E. Burgess, Pioneer Odyssey, NASA SP-396, 2nd edition (NASA, Washington, D. C., 1977).
  43. D. L. Coffeen, “Optical Polarization Measurements of the Jupiter Atmosphere at 103° Phase Angle,” J. Geophys. Res. 79, 3645–3652 (1974).
    [Crossref]
  44. M. G. Tomasko, R. A. West, and N. D. Castillo, “Photometry and Polarimetry of Jupiter at Large Phase Angles. 1. Analysis of Imaging Data of a Prominent Belt and a Zone from Pioneer 10,” Icarus 33, 558–592 (1978).
    [Crossref]
  45. R. Eiden, “The Elliptical Polarization of Light Scattered by a Volume of Atmospheric Air,” Appl. Opt. 5, 569–575 (1966).
    [Crossref] [PubMed]
  46. J. C. Kemp, R. D. Wolstencroft, and J. B. Swedlund, “Circular Polarization: Jupiter and Other Planets,” Nature 232, 165–168 (1971).
    [Crossref] [PubMed]
  47. J. E. Hansen, “Circular Polarization of Sunlight Reflected by Clouds,” J. Atmos. Sci. 28, 1515–1516 (1971).
    [Crossref]
  48. Y. Kawata, “Circular Polarization of Sunlight Reflected by Planetary Atmospheres,” Icarus 33, 217–232 (1978).
    [Crossref]

1979 (1)

L. D. Travis, D. L. Coffeen, J. E. Hansen, K. Kawabata, A. A. Lacis, W. A. Lane, S. S. Limaye, and P. H. Stone, “Orbiter Cloud Photopolarimeter Investigation,” Science 203, 781–785 (1979).
[Crossref] [PubMed]

1978 (2)

M. G. Tomasko, R. A. West, and N. D. Castillo, “Photometry and Polarimetry of Jupiter at Large Phase Angles. 1. Analysis of Imaging Data of a Prominent Belt and a Zone from Pioneer 10,” Icarus 33, 558–592 (1978).
[Crossref]

Y. Kawata, “Circular Polarization of Sunlight Reflected by Planetary Atmospheres,” Icarus 33, 217–232 (1978).
[Crossref]

1976 (1)

1975 (2)

It should be noted that the Venus particles form more of a“haze” than a “cloud.”K. Kawabata and J. E. Hansen [“Interpretation of the Variation of Polarization over the Disk of Venus, “ J. Atmos. Sci. 32, 1133–1139 (1975)] deduce a photon mean free path of ∼5 km at the level where the vertical cloud optical depth is unity, compared to a mean free path of ∼0.1 km in typical terrestrial clouds.
[Crossref]

D. L. Coffeen, J. Hämeen-Anttila, and R. H. Toubhans, “Airborne Infrared Polarimeter,” Space Sci. Instrum. 1, 161–175 (1975).

1974 (4)

J. E. Hansen and J. W. Hovenier, “Interpretation of the Polarization of Venus,” J. Atmos. Sci. 31, 1137–1160 (1974).
[Crossref]

C. N. Adams, G. N. Plass, and G. W. Kattawar, “The Influence of Ozone and Aerosols on the Brightness and Color of the Twilight Sky,” J. Atmos. Sci. 31, 1662–1674 (1974).
[Crossref]

J. E. Hansen and L. D. Travis, “Light Scattering in Planetary Atmospheres,” Space Sci. Rev. 16, 527–610 (1974).
[Crossref]

D. L. Coffeen, “Optical Polarization Measurements of the Jupiter Atmosphere at 103° Phase Angle,” J. Geophys. Res. 79, 3645–3652 (1974).
[Crossref]

1971 (5)

J. C. Kemp, R. D. Wolstencroft, and J. B. Swedlund, “Circular Polarization: Jupiter and Other Planets,” Nature 232, 165–168 (1971).
[Crossref] [PubMed]

J. E. Hansen, “Circular Polarization of Sunlight Reflected by Clouds,” J. Atmos. Sci. 28, 1515–1516 (1971).
[Crossref]

K. L. Coulson, “On the Solar Radiation Field in a Polluted Atmosphere,” J. Quant. Spectrosc. Radiat. Transfer 11, 739–755 (1971).
[Crossref]

W. McD. Napier, “The Ashen Light on Venus,” Planet. Space Sci. 19, 1049–1051 (1971).
[Crossref]

J. E. Hansen, “Multiple Scattering of Polarized Light in Planetary Atmospheres. Part II. Sunlight Reflected by Terrestrial Water Clouds,” J. Atmos. Sci. 28, 1400–1426 (1971).
[Crossref]

1970 (1)

A. Dollfus and D. L. Coffeen, “Polarization of Venus. I. Disk Observations,” Astron. Astrophys. 8, 251–266 (1970).

1969 (2)

D. L. Coffeen, “Wavelength Dependence of Polarization. XVI. Atmosphere of Venus,” Astron. J. 74, 446–460 (1969).
[Crossref]

F. Unz, “Die Konzentration des Aerosols in Troposphäre und Stratosphäre aus Messungen der Polarisation der Himmelsstrahlung im Zenit,” Beitr. Phys. Atmos. 42, 1–35 (1969).

1968 (2)

A. Arking and J. Potter, “The Phase Curve of Venus and the Nature of its Clouds,” J. Atmos. Sci. 25, 617–628 (1968).
[Crossref]

A. J. Stratton, “Optical and Radio Refraction on Venus,” J. Atmos. Sci. 25, 666–667 (1968).
[Crossref]

1966 (1)

1964 (1)

K. Bullrich, “Scattered Radiation in the Atmosphere and the Natural Aerosol,” Adv. Geophys. 10, 99–260, 1964.
[Crossref]

1962 (1)

T. Gehrels, “Wavelength Dependence of the Polarization of the Sunlit Sky,” J. Opt. Soc. Amer. 52, 1164–1173 (1962).
[Crossref]

1961 (1)

E. de Bary, K. Bullrich, and D. Lorenz, “Messungen der Himmelsstrahlung und deren Polarisationsgrad während der Sonnenfinsternis am 15.2.1961 in Viareggio (Italien),” Geofis. Pura Appl. 48, 193–198 (1961).
[Crossref]

1955 (1)

1954 (1)

S. Chandrasekhar and D. D. Elbert, “The Illumination and Polarization of the Sunlit Sky on Rayleigh Scattering,” Trans. Am. Philos. Soc. 44, 643–728 (1954).
[Crossref]

Adams, C. N.

C. N. Adams, G. N. Plass, and G. W. Kattawar, “The Influence of Ozone and Aerosols on the Brightness and Color of the Twilight Sky,” J. Atmos. Sci. 31, 1662–1674 (1974).
[Crossref]

Arking, A.

A. Arking and J. Potter, “The Phase Curve of Venus and the Nature of its Clouds,” J. Atmos. Sci. 25, 617–628 (1968).
[Crossref]

Bullrich, K.

K. Bullrich, “Scattered Radiation in the Atmosphere and the Natural Aerosol,” Adv. Geophys. 10, 99–260, 1964.
[Crossref]

E. de Bary, K. Bullrich, and D. Lorenz, “Messungen der Himmelsstrahlung und deren Polarisationsgrad während der Sonnenfinsternis am 15.2.1961 in Viareggio (Italien),” Geofis. Pura Appl. 48, 193–198 (1961).
[Crossref]

Burgess, E.

R. O. Fimmel, W. Swindell, and E. Burgess, Pioneer Odyssey, NASA SP-396, 2nd edition (NASA, Washington, D. C., 1977).

Castillo, N. D.

M. G. Tomasko, R. A. West, and N. D. Castillo, “Photometry and Polarimetry of Jupiter at Large Phase Angles. 1. Analysis of Imaging Data of a Prominent Belt and a Zone from Pioneer 10,” Icarus 33, 558–592 (1978).
[Crossref]

Chandrasekhar, S.

S. Chandrasekhar and D. D. Elbert, “The Illumination and Polarization of the Sunlit Sky on Rayleigh Scattering,” Trans. Am. Philos. Soc. 44, 643–728 (1954).
[Crossref]

S. Chandrasekhar, Radiative Transfer (Dover, New York, 1960) (reprint).

Coffeen, D.

Preliminary data by L. Travis, D. Coffeen, W. Lane, and J. Hansen, (unpublished).

Coffeen, D. L.

L. D. Travis, D. L. Coffeen, J. E. Hansen, K. Kawabata, A. A. Lacis, W. A. Lane, S. S. Limaye, and P. H. Stone, “Orbiter Cloud Photopolarimeter Investigation,” Science 203, 781–785 (1979).
[Crossref] [PubMed]

D. L. Coffeen, J. Hämeen-Anttila, and R. H. Toubhans, “Airborne Infrared Polarimeter,” Space Sci. Instrum. 1, 161–175 (1975).

D. L. Coffeen, “Optical Polarization Measurements of the Jupiter Atmosphere at 103° Phase Angle,” J. Geophys. Res. 79, 3645–3652 (1974).
[Crossref]

A. Dollfus and D. L. Coffeen, “Polarization of Venus. I. Disk Observations,” Astron. Astrophys. 8, 251–266 (1970).

D. L. Coffeen, “Wavelength Dependence of Polarization. XVI. Atmosphere of Venus,” Astron. J. 74, 446–460 (1969).
[Crossref]

J. E. Hansen and D. L. Coffeen, “Analysis of Cloud Polarization Measurements,” Proceedings of the Conference on Cloud Physics of the American Meteorological Society, edited by R. L. Lavoie and G. A. Dawson, 350–356 (1974).

See Figure 17 in D. L. Coffeen and J. E. Hansen, “Polarization Studies of Planetary Atmospheres,” in Planets, Stars and Nebulae Studied with Photopolarimetry, edited by T. Gehrels (University of Arizona, Tucson, 1974).

Coulson, K. L.

K. L. Coulson, “On the Solar Radiation Field in a Polluted Atmosphere,” J. Quant. Spectrosc. Radiat. Transfer 11, 739–755 (1971).
[Crossref]

K. L. Coulson, “Atmospheric Turbidity Determinations by Skylight Measurements at the Mauna Loa Observatory,” Contributions in Atmospheric Science No. 13 (University of California, Davis, 1977).

Darwin, C.

C. Darwin, Journal of Researches into the Natural History and Geology of the Countries Visited during the Voyage of the H.M.S. Beagle (Heritage, New York, 1957) (reprint edition).

de Bary, E.

E. de Bary, K. Bullrich, and D. Lorenz, “Messungen der Himmelsstrahlung und deren Polarisationsgrad während der Sonnenfinsternis am 15.2.1961 in Viareggio (Italien),” Geofis. Pura Appl. 48, 193–198 (1961).
[Crossref]

Dollfus, A.

A. Dollfus and D. L. Coffeen, “Polarization of Venus. I. Disk Observations,” Astron. Astrophys. 8, 251–266 (1970).

A. Dollfus, Thesis Univ. of Paris, 1955 (in English translation as NASA TT F-188, Washington, D.C., 1964).

Eiden, R.

Elbert, D. D.

S. Chandrasekhar and D. D. Elbert, “The Illumination and Polarization of the Sunlit Sky on Rayleigh Scattering,” Trans. Am. Philos. Soc. 44, 643–728 (1954).
[Crossref]

Fimmel, R. O.

R. O. Fimmel, W. Swindell, and E. Burgess, Pioneer Odyssey, NASA SP-396, 2nd edition (NASA, Washington, D. C., 1977).

Garriott, O. K.

O. K. Garriott, “Visual Observations from Space,” Technical Digest of OSA Topical Meeting on Meteorological Optics, Keystone, Colorado, August, 1978 (unpublished).

Gehrels, T.

T. Gehrels, “Wavelength Dependence of the Polarization of the Sunlit Sky,” J. Opt. Soc. Amer. 52, 1164–1173 (1962).
[Crossref]

Hämeen-Anttila, J.

D. L. Coffeen, J. Hämeen-Anttila, and R. H. Toubhans, “Airborne Infrared Polarimeter,” Space Sci. Instrum. 1, 161–175 (1975).

Hansen, J.

Preliminary data by L. Travis, D. Coffeen, W. Lane, and J. Hansen, (unpublished).

Hansen, J. E.

L. D. Travis, D. L. Coffeen, J. E. Hansen, K. Kawabata, A. A. Lacis, W. A. Lane, S. S. Limaye, and P. H. Stone, “Orbiter Cloud Photopolarimeter Investigation,” Science 203, 781–785 (1979).
[Crossref] [PubMed]

It should be noted that the Venus particles form more of a“haze” than a “cloud.”K. Kawabata and J. E. Hansen [“Interpretation of the Variation of Polarization over the Disk of Venus, “ J. Atmos. Sci. 32, 1133–1139 (1975)] deduce a photon mean free path of ∼5 km at the level where the vertical cloud optical depth is unity, compared to a mean free path of ∼0.1 km in typical terrestrial clouds.
[Crossref]

J. E. Hansen and J. W. Hovenier, “Interpretation of the Polarization of Venus,” J. Atmos. Sci. 31, 1137–1160 (1974).
[Crossref]

J. E. Hansen and L. D. Travis, “Light Scattering in Planetary Atmospheres,” Space Sci. Rev. 16, 527–610 (1974).
[Crossref]

J. E. Hansen, “Multiple Scattering of Polarized Light in Planetary Atmospheres. Part II. Sunlight Reflected by Terrestrial Water Clouds,” J. Atmos. Sci. 28, 1400–1426 (1971).
[Crossref]

J. E. Hansen, “Circular Polarization of Sunlight Reflected by Clouds,” J. Atmos. Sci. 28, 1515–1516 (1971).
[Crossref]

J. E. Hansen and D. L. Coffeen, “Analysis of Cloud Polarization Measurements,” Proceedings of the Conference on Cloud Physics of the American Meteorological Society, edited by R. L. Lavoie and G. A. Dawson, 350–356 (1974).

See Figure 17 in D. L. Coffeen and J. E. Hansen, “Polarization Studies of Planetary Atmospheres,” in Planets, Stars and Nebulae Studied with Photopolarimetry, edited by T. Gehrels (University of Arizona, Tucson, 1974).

Hitzfelder, S. J.

Hovenier, J. W.

J. E. Hansen and J. W. Hovenier, “Interpretation of the Polarization of Venus,” J. Atmos. Sci. 31, 1137–1160 (1974).
[Crossref]

Humphreys, W. J.

W. J. Humphreys, Physics of the Air (Franklin Institute, Philadelphia, 1920).

Johnson, J. C.

J. C. Johnson, Physical Meteorology (MIT, Cambridge, Mass. and Wiley, N.Y., 1954).

Kattawar, G. W.

G. W. Kattawar, G. N. Plass, and S. J. Hitzfelder, “Multiple scattered radiation emerging from Rayleigh and continental haze layers. 1: Radiance, polarization, and neutral points,” Appl. Opt. 15, 632–647 (1976).
[Crossref] [PubMed]

C. N. Adams, G. N. Plass, and G. W. Kattawar, “The Influence of Ozone and Aerosols on the Brightness and Color of the Twilight Sky,” J. Atmos. Sci. 31, 1662–1674 (1974).
[Crossref]

Kawabata, K.

L. D. Travis, D. L. Coffeen, J. E. Hansen, K. Kawabata, A. A. Lacis, W. A. Lane, S. S. Limaye, and P. H. Stone, “Orbiter Cloud Photopolarimeter Investigation,” Science 203, 781–785 (1979).
[Crossref] [PubMed]

It should be noted that the Venus particles form more of a“haze” than a “cloud.”K. Kawabata and J. E. Hansen [“Interpretation of the Variation of Polarization over the Disk of Venus, “ J. Atmos. Sci. 32, 1133–1139 (1975)] deduce a photon mean free path of ∼5 km at the level where the vertical cloud optical depth is unity, compared to a mean free path of ∼0.1 km in typical terrestrial clouds.
[Crossref]

Kawata, Y.

Y. Kawata, “Circular Polarization of Sunlight Reflected by Planetary Atmospheres,” Icarus 33, 217–232 (1978).
[Crossref]

Keldysh, M. V.

M. V. Keldysh, “Venus Exploration with the Automatic Stations Venera 9 and Venera 10,” paper presented at the XIXth COSPAR Meeting, Philadelphia, Pa., 14–19 June, 1976, 43 pp. (unpublished);A. S. Selivanov, V. P. Chemodanov, M. K. Naraeva, A. S. Panfilov, M. A. Gerasimov, and I. I. Kobzeva, “A Television Experiment on the Surface of Venus,” translation of Kosm. Issled. 14, 674–677 (1976);A. S. Selivanov, A. S. Panfilov, M. K. Naraeva, V. P. Chemodanov, M. I. Bokhonov, and M. A. Gerasimov, “Photometric Analysis of Panoramas on the Surface of Venus,” translation of Kosm. Issled. 14, 678–686 (1976).

Kemp, J. C.

J. C. Kemp, R. D. Wolstencroft, and J. B. Swedlund, “Circular Polarization: Jupiter and Other Planets,” Nature 232, 165–168 (1971).
[Crossref] [PubMed]

Kondratyev, K. Ya.

K. Ya. Kondratyev, Radiation in the Atmosphere (Academic, New York, 1969).

Lacis, A. A.

L. D. Travis, D. L. Coffeen, J. E. Hansen, K. Kawabata, A. A. Lacis, W. A. Lane, S. S. Limaye, and P. H. Stone, “Orbiter Cloud Photopolarimeter Investigation,” Science 203, 781–785 (1979).
[Crossref] [PubMed]

Lane, W.

Preliminary data by L. Travis, D. Coffeen, W. Lane, and J. Hansen, (unpublished).

Lane, W. A.

L. D. Travis, D. L. Coffeen, J. E. Hansen, K. Kawabata, A. A. Lacis, W. A. Lane, S. S. Limaye, and P. H. Stone, “Orbiter Cloud Photopolarimeter Investigation,” Science 203, 781–785 (1979).
[Crossref] [PubMed]

Lillie, C.

Preliminary data from C. Lillie (unpublished).

Limaye, S. S.

L. D. Travis, D. L. Coffeen, J. E. Hansen, K. Kawabata, A. A. Lacis, W. A. Lane, S. S. Limaye, and P. H. Stone, “Orbiter Cloud Photopolarimeter Investigation,” Science 203, 781–785 (1979).
[Crossref] [PubMed]

Lorenz, D.

E. de Bary, K. Bullrich, and D. Lorenz, “Messungen der Himmelsstrahlung und deren Polarisationsgrad während der Sonnenfinsternis am 15.2.1961 in Viareggio (Italien),” Geofis. Pura Appl. 48, 193–198 (1961).
[Crossref]

McCartney, E. J.

E. J. McCartney, Optics of the Atmosphere (Wiley, New York, 1976).

Minnaert, M.

M. Minnaert, The Nature of Light and Colour in the Open Air (Dover, New York, 1954) (reprint).

Moore, P.

P. Moore, The Planet Venus, 3rd ed. (Macmillan, New York, 1960).

Napier, W. McD.

W. McD. Napier, “The Ashen Light on Venus,” Planet. Space Sci. 19, 1049–1051 (1971).
[Crossref]

Plass, G. N.

G. W. Kattawar, G. N. Plass, and S. J. Hitzfelder, “Multiple scattered radiation emerging from Rayleigh and continental haze layers. 1: Radiance, polarization, and neutral points,” Appl. Opt. 15, 632–647 (1976).
[Crossref] [PubMed]

C. N. Adams, G. N. Plass, and G. W. Kattawar, “The Influence of Ozone and Aerosols on the Brightness and Color of the Twilight Sky,” J. Atmos. Sci. 31, 1662–1674 (1974).
[Crossref]

Potter, J.

A. Arking and J. Potter, “The Phase Curve of Venus and the Nature of its Clouds,” J. Atmos. Sci. 25, 617–628 (1968).
[Crossref]

Rennilson, J. J.

E. M. Shoemaker, J. J. Rennilson, and E. A. Whitaker, “Eclipse of Sun by Earth, as Seen from Surveyor III,” Surveyor Project Final Report, Part II. Science Results (NASA Technical Report 32-1265, Jet Propulsion Lab, Pasadena, 1968).

Rozenberg, G. V.

G. V. Rozenberg, Twilight: A Study in Atmospheric Optics (Plenum, New York, 1966).

Shoemaker, E. M.

E. M. Shoemaker, J. J. Rennilson, and E. A. Whitaker, “Eclipse of Sun by Earth, as Seen from Surveyor III,” Surveyor Project Final Report, Part II. Science Results (NASA Technical Report 32-1265, Jet Propulsion Lab, Pasadena, 1968).

Shurcliff, W. A.

Stone, P. H.

L. D. Travis, D. L. Coffeen, J. E. Hansen, K. Kawabata, A. A. Lacis, W. A. Lane, S. S. Limaye, and P. H. Stone, “Orbiter Cloud Photopolarimeter Investigation,” Science 203, 781–785 (1979).
[Crossref] [PubMed]

Stratton, A. J.

A. J. Stratton, “Optical and Radio Refraction on Venus,” J. Atmos. Sci. 25, 666–667 (1968).
[Crossref]

Swedlund, J. B.

J. C. Kemp, R. D. Wolstencroft, and J. B. Swedlund, “Circular Polarization: Jupiter and Other Planets,” Nature 232, 165–168 (1971).
[Crossref] [PubMed]

Swindell, W.

R. O. Fimmel, W. Swindell, and E. Burgess, Pioneer Odyssey, NASA SP-396, 2nd edition (NASA, Washington, D. C., 1977).

Tomasko, M. G.

M. G. Tomasko, R. A. West, and N. D. Castillo, “Photometry and Polarimetry of Jupiter at Large Phase Angles. 1. Analysis of Imaging Data of a Prominent Belt and a Zone from Pioneer 10,” Icarus 33, 558–592 (1978).
[Crossref]

Toubhans, R. H.

D. L. Coffeen, J. Hämeen-Anttila, and R. H. Toubhans, “Airborne Infrared Polarimeter,” Space Sci. Instrum. 1, 161–175 (1975).

Travis, L.

Preliminary data by L. Travis, D. Coffeen, W. Lane, and J. Hansen, (unpublished).

Travis, L. D.

L. D. Travis, D. L. Coffeen, J. E. Hansen, K. Kawabata, A. A. Lacis, W. A. Lane, S. S. Limaye, and P. H. Stone, “Orbiter Cloud Photopolarimeter Investigation,” Science 203, 781–785 (1979).
[Crossref] [PubMed]

J. E. Hansen and L. D. Travis, “Light Scattering in Planetary Atmospheres,” Space Sci. Rev. 16, 527–610 (1974).
[Crossref]

Tricker, R. A. R.

R. A. R. Tricker, Introduction to Meteorological Optics (American Elsevier, New York, 1970).

Unz, F.

F. Unz, “Die Konzentration des Aerosols in Troposphäre und Stratosphäre aus Messungen der Polarisation der Himmelsstrahlung im Zenit,” Beitr. Phys. Atmos. 42, 1–35 (1969).

van de Hulst, H. C.

H. C. van de Hulst, “Scattering in the Atmospheres of the Earth and Planets,” in The Atmospheres of the Earth and Planets, edited by G. P. Kuiper (University of Chicago, Chicago, 1949).

von Helmholtz, H.

H. von Helmholtz, Physiological Optics, English edition, translated by J. P. C. Southall (Optical Society of America, Washington, D.C., 1924), especially Vol. II, pp. 301–308;E. J. Gording, “A Report on Haidinger Brushes,” Am. J. Optom. Arch. Am. Acad. Optom. 27, 604–610 (1951);L. L. Sloan and H. A. Naquin, “A Quantitative Test for Determining the Visibility of the Haidinger Brushes: Clinical Applications,” Am. J. Ophthalmol. 40, 393–406 (1955).
[Crossref] [PubMed]

West, R. A.

M. G. Tomasko, R. A. West, and N. D. Castillo, “Photometry and Polarimetry of Jupiter at Large Phase Angles. 1. Analysis of Imaging Data of a Prominent Belt and a Zone from Pioneer 10,” Icarus 33, 558–592 (1978).
[Crossref]

Whitaker, E. A.

E. M. Shoemaker, J. J. Rennilson, and E. A. Whitaker, “Eclipse of Sun by Earth, as Seen from Surveyor III,” Surveyor Project Final Report, Part II. Science Results (NASA Technical Report 32-1265, Jet Propulsion Lab, Pasadena, 1968).

Wolstencroft, R. D.

J. C. Kemp, R. D. Wolstencroft, and J. B. Swedlund, “Circular Polarization: Jupiter and Other Planets,” Nature 232, 165–168 (1971).
[Crossref] [PubMed]

Adv. Geophys. (1)

K. Bullrich, “Scattered Radiation in the Atmosphere and the Natural Aerosol,” Adv. Geophys. 10, 99–260, 1964.
[Crossref]

Appl. Opt. (2)

Astron. Astrophys. (1)

A. Dollfus and D. L. Coffeen, “Polarization of Venus. I. Disk Observations,” Astron. Astrophys. 8, 251–266 (1970).

Astron. J. (1)

D. L. Coffeen, “Wavelength Dependence of Polarization. XVI. Atmosphere of Venus,” Astron. J. 74, 446–460 (1969).
[Crossref]

Beitr. Phys. Atmos. (1)

F. Unz, “Die Konzentration des Aerosols in Troposphäre und Stratosphäre aus Messungen der Polarisation der Himmelsstrahlung im Zenit,” Beitr. Phys. Atmos. 42, 1–35 (1969).

Geofis. Pura Appl. (1)

E. de Bary, K. Bullrich, and D. Lorenz, “Messungen der Himmelsstrahlung und deren Polarisationsgrad während der Sonnenfinsternis am 15.2.1961 in Viareggio (Italien),” Geofis. Pura Appl. 48, 193–198 (1961).
[Crossref]

Icarus (2)

M. G. Tomasko, R. A. West, and N. D. Castillo, “Photometry and Polarimetry of Jupiter at Large Phase Angles. 1. Analysis of Imaging Data of a Prominent Belt and a Zone from Pioneer 10,” Icarus 33, 558–592 (1978).
[Crossref]

Y. Kawata, “Circular Polarization of Sunlight Reflected by Planetary Atmospheres,” Icarus 33, 217–232 (1978).
[Crossref]

J. Atmos. Sci. (7)

J. E. Hansen, “Circular Polarization of Sunlight Reflected by Clouds,” J. Atmos. Sci. 28, 1515–1516 (1971).
[Crossref]

A. J. Stratton, “Optical and Radio Refraction on Venus,” J. Atmos. Sci. 25, 666–667 (1968).
[Crossref]

A. Arking and J. Potter, “The Phase Curve of Venus and the Nature of its Clouds,” J. Atmos. Sci. 25, 617–628 (1968).
[Crossref]

C. N. Adams, G. N. Plass, and G. W. Kattawar, “The Influence of Ozone and Aerosols on the Brightness and Color of the Twilight Sky,” J. Atmos. Sci. 31, 1662–1674 (1974).
[Crossref]

J. E. Hansen, “Multiple Scattering of Polarized Light in Planetary Atmospheres. Part II. Sunlight Reflected by Terrestrial Water Clouds,” J. Atmos. Sci. 28, 1400–1426 (1971).
[Crossref]

J. E. Hansen and J. W. Hovenier, “Interpretation of the Polarization of Venus,” J. Atmos. Sci. 31, 1137–1160 (1974).
[Crossref]

It should be noted that the Venus particles form more of a“haze” than a “cloud.”K. Kawabata and J. E. Hansen [“Interpretation of the Variation of Polarization over the Disk of Venus, “ J. Atmos. Sci. 32, 1133–1139 (1975)] deduce a photon mean free path of ∼5 km at the level where the vertical cloud optical depth is unity, compared to a mean free path of ∼0.1 km in typical terrestrial clouds.
[Crossref]

J. Geophys. Res. (1)

D. L. Coffeen, “Optical Polarization Measurements of the Jupiter Atmosphere at 103° Phase Angle,” J. Geophys. Res. 79, 3645–3652 (1974).
[Crossref]

J. Opt. Soc. Am. (1)

J. Opt. Soc. Amer. (1)

T. Gehrels, “Wavelength Dependence of the Polarization of the Sunlit Sky,” J. Opt. Soc. Amer. 52, 1164–1173 (1962).
[Crossref]

J. Quant. Spectrosc. Radiat. Transfer (1)

K. L. Coulson, “On the Solar Radiation Field in a Polluted Atmosphere,” J. Quant. Spectrosc. Radiat. Transfer 11, 739–755 (1971).
[Crossref]

Nature (1)

J. C. Kemp, R. D. Wolstencroft, and J. B. Swedlund, “Circular Polarization: Jupiter and Other Planets,” Nature 232, 165–168 (1971).
[Crossref] [PubMed]

Planet. Space Sci. (1)

W. McD. Napier, “The Ashen Light on Venus,” Planet. Space Sci. 19, 1049–1051 (1971).
[Crossref]

Science (1)

L. D. Travis, D. L. Coffeen, J. E. Hansen, K. Kawabata, A. A. Lacis, W. A. Lane, S. S. Limaye, and P. H. Stone, “Orbiter Cloud Photopolarimeter Investigation,” Science 203, 781–785 (1979).
[Crossref] [PubMed]

Space Sci. Instrum. (1)

D. L. Coffeen, J. Hämeen-Anttila, and R. H. Toubhans, “Airborne Infrared Polarimeter,” Space Sci. Instrum. 1, 161–175 (1975).

Space Sci. Rev. (1)

J. E. Hansen and L. D. Travis, “Light Scattering in Planetary Atmospheres,” Space Sci. Rev. 16, 527–610 (1974).
[Crossref]

Trans. Am. Philos. Soc. (1)

S. Chandrasekhar and D. D. Elbert, “The Illumination and Polarization of the Sunlit Sky on Rayleigh Scattering,” Trans. Am. Philos. Soc. 44, 643–728 (1954).
[Crossref]

Other (22)

H. von Helmholtz, Physiological Optics, English edition, translated by J. P. C. Southall (Optical Society of America, Washington, D.C., 1924), especially Vol. II, pp. 301–308;E. J. Gording, “A Report on Haidinger Brushes,” Am. J. Optom. Arch. Am. Acad. Optom. 27, 604–610 (1951);L. L. Sloan and H. A. Naquin, “A Quantitative Test for Determining the Visibility of the Haidinger Brushes: Clinical Applications,” Am. J. Ophthalmol. 40, 393–406 (1955).
[Crossref] [PubMed]

S. Chandrasekhar, Radiative Transfer (Dover, New York, 1960) (reprint).

C. Darwin, Journal of Researches into the Natural History and Geology of the Countries Visited during the Voyage of the H.M.S. Beagle (Heritage, New York, 1957) (reprint edition).

H. C. van de Hulst, “Scattering in the Atmospheres of the Earth and Planets,” in The Atmospheres of the Earth and Planets, edited by G. P. Kuiper (University of Chicago, Chicago, 1949).

W. J. Humphreys, Physics of the Air (Franklin Institute, Philadelphia, 1920).

M. Minnaert, The Nature of Light and Colour in the Open Air (Dover, New York, 1954) (reprint).

J. C. Johnson, Physical Meteorology (MIT, Cambridge, Mass. and Wiley, N.Y., 1954).

G. V. Rozenberg, Twilight: A Study in Atmospheric Optics (Plenum, New York, 1966).

K. Ya. Kondratyev, Radiation in the Atmosphere (Academic, New York, 1969).

R. A. R. Tricker, Introduction to Meteorological Optics (American Elsevier, New York, 1970).

E. J. McCartney, Optics of the Atmosphere (Wiley, New York, 1976).

J. E. Hansen and D. L. Coffeen, “Analysis of Cloud Polarization Measurements,” Proceedings of the Conference on Cloud Physics of the American Meteorological Society, edited by R. L. Lavoie and G. A. Dawson, 350–356 (1974).

K. L. Coulson, “Atmospheric Turbidity Determinations by Skylight Measurements at the Mauna Loa Observatory,” Contributions in Atmospheric Science No. 13 (University of California, Davis, 1977).

O. K. Garriott, “Visual Observations from Space,” Technical Digest of OSA Topical Meeting on Meteorological Optics, Keystone, Colorado, August, 1978 (unpublished).

A. Dollfus, Thesis Univ. of Paris, 1955 (in English translation as NASA TT F-188, Washington, D.C., 1964).

Preliminary data from C. Lillie (unpublished).

Preliminary data by L. Travis, D. Coffeen, W. Lane, and J. Hansen, (unpublished).

E. M. Shoemaker, J. J. Rennilson, and E. A. Whitaker, “Eclipse of Sun by Earth, as Seen from Surveyor III,” Surveyor Project Final Report, Part II. Science Results (NASA Technical Report 32-1265, Jet Propulsion Lab, Pasadena, 1968).

P. Moore, The Planet Venus, 3rd ed. (Macmillan, New York, 1960).

M. V. Keldysh, “Venus Exploration with the Automatic Stations Venera 9 and Venera 10,” paper presented at the XIXth COSPAR Meeting, Philadelphia, Pa., 14–19 June, 1976, 43 pp. (unpublished);A. S. Selivanov, V. P. Chemodanov, M. K. Naraeva, A. S. Panfilov, M. A. Gerasimov, and I. I. Kobzeva, “A Television Experiment on the Surface of Venus,” translation of Kosm. Issled. 14, 674–677 (1976);A. S. Selivanov, A. S. Panfilov, M. K. Naraeva, V. P. Chemodanov, M. I. Bokhonov, and M. A. Gerasimov, “Photometric Analysis of Panoramas on the Surface of Venus,” translation of Kosm. Issled. 14, 678–686 (1976).

See Figure 17 in D. L. Coffeen and J. E. Hansen, “Polarization Studies of Planetary Atmospheres,” in Planets, Stars and Nebulae Studied with Photopolarimetry, edited by T. Gehrels (University of Arizona, Tucson, 1974).

R. O. Fimmel, W. Swindell, and E. Burgess, Pioneer Odyssey, NASA SP-396, 2nd edition (NASA, Washington, D. C., 1977).

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Figures (24)

FIG. 1
FIG. 1

“Neutral lines,” the boundaries between regions of positive and regions of negative polarization, in the clear daytime sky. The entire hemisphere of the sky is shown, with altitude circles every 10°. Neutral lines are given for each of seven different zenith angles of the sun, ranging from 30° to 87°. On the left are observations made by Dorno on 17 May 1917 at Davos, Switzerland; on the right are computations for multiple Rayleigh scattering using Chandrasekhar’s solution. The neutral lines intersect the solar vertical plane on the well-known neutral points of zero polarization, the Brewster, Babinet, and Arago points. These points and the shapes of neutral lines result from multiple scattering within the molecular atmosphere. The excellent agreement between observations and theory is evidence for the correctness and applicability of Chandrasekhar’s solution (after Chandrasekhar and Elbert14).

FIG. 2
FIG. 2

Computed positions (μ = cosine of zenith angle) of the neutral points in the solar vertical plane in a clear Rayleigh atmosphere as a function of the vertical optical depth (τ). The sun is at 79°.15 zenith angle; results are shown for two ground albedos (A). Note the divergence and eventual disappearance of the neutral points as the optical depth increases (after Kattawar et al.15).

FIG. 3
FIG. 3

Typical scattering diagrams (phase functions) for six size distributions of dielectric spheres. Unpolarized light is incident from the left. The scattered intensity is plotted as a function of direction. The refractive index m, the wavelength λ, and the effective variance Veff of the size distribution are held constant while the effective radius reff (μm) is varied.12 As the circumference-to-wavelength ratio increases, the scattering becomes more concentrated about the forward direction. Thus the angular width of an aureole about the sun is an indication of the mean size of the atmospheric aerosols.

FIG. 4
FIG. 4

Measurements of the maximum degree of polarization (occurring ∼90° from the sun, in the solar vertical plane) as a function of increasing solar elevation in clear (Davis and Los Angeles, California) and polluted (Los Angeles) atmospheres. Note the reduced value of the maximum in the polluted cases, and the rapid decrease during the day, attributed to build-up of smog and motion of the 90°-phase-angle point toward the horizon (after Coulson16).

FIG. 5
FIG. 5

Linear polarization of zenith skylight measured from an ascending-balloon instrument, in the green (535 nm) and red (725 nm). The solar zenith angle was between 59° and 85° for all three flights. The variations of polarization with altitude indicate variations in the aerosol concentration (after Unz17).

FIG. 6
FIG. 6

Extinction efficiency for nonabsorbing spheres of refractive index 1.33, as a function of size parameter (ratio of circumference to wavelength). For a given wavelength this shows the variation of scattering efficiency with particle size; for a given size particle, it shows the wavelength dependence of the scattered light. Results are given for four values of the “width” b (the effective variance) of a distribution of sizes (after Hansen and Travis12).

FIG. 7
FIG. 7

Calculations of the brightness of skylight for the sun 6° below the horizon, as a function of wavelength and zenith angle of observation (in the solar vertical plane on the sunward side). The model includes spherical geometry, atmospheric refraction, scattering by gas and by standard aerosols, and ozone absorption, but is restricted to single scattering. The predominant colors of twilight are reproduced by the model. The minimum near 0.6 μm is due to ozone absorption, which is thus responsible for the purple and blue colors at twilight (after Adams et al.19).

FIG. 8
FIG. 8

Observations of the polarization of the clear sky, near the zenith, as the sun rises. The data were taken in west Texas, at wavelengths of 355 nm (U), 529 nm (G), and 943 nm (I). The 94% polarization expected for single scattering by pure air is reduced by multiple scattering, by ground reflection (after sunrise), and by aerosol scattering (especially well before sunrise when the illuminated region may have a high aerosol-to-gas scattering ratio) (after Gehrels20).

FIG. 9
FIG. 9

Observations of zenith sky polarization at sunrise taken from Mauna Loa Observatory, Hawaii, 19 February 1977. The structure at −6° to −3° sun elevation, in the infrared, is typical, although the position and depth of the minimum vary considerably from day to day, related to the atmospheric turbidity. The minimum at −4° indicates an aerosol layer with maximum density at ∼16 km (after Coulson21).

FIG. 10
FIG. 10

Measurements of the degree of polarization of skylight, 90° from the sun in the solar vertical plane, taken 15 February 1961 during the course of a total solar eclipse, and again 16 February 1961 for comparison. During totality the light originates outside the shadow zone, and is multiply scattered to the observer. At all three wavelengths (red —, green …, and ultraviolet - - -) the polarization drops to ∼0 at totality, indicating the nearly perfect diffusion by multiple scattering (after de Bary et al.22).

FIG. 11
FIG. 11

Comparison of theoretical curves with observations (dots) of the intensity and polarization of light scattered upward by a layer of maritime altostratus clouds. The wavelength of observation is 2. 2 μm. Note the striking cloudbows in the polarization. By varying the model parameters it is possible to deduce the effective particle radius a and the effective variance of the size distribution b, and to set limits on the optical depth of the cloud τ (after Hansen and Coffeen24).

FIG. 12
FIG. 12

Calculated intensity and percent polarization of sunlight reflected by a plane-parallel water cloud with the sun overhead. The wavelength is 1.2 μm and the results are shown for several optical thicknesses τ as a function of the zenith angle of the reflected light. For zenith angle 0° the observer is looking down to the nadir, at phase angle 0°. The calculations are for a size distribution of water drops, with a mean effective radius 6 μm and an effective variance 1/9. As optical thickness of the cloud increases, the reflected intensity increases but loses the details of the single scattering phase function; the reflected polarization decreases, but retains the details of single scattering—cloudbow, glory, etc. (after Hansen25).

FIG. 13
FIG. 13

Measurements of percent polarization of sunlight reflected by two cloud systems, using a tracking infrared polarimeter on the NASA CV-990 jet aircraft. The thick altocumulus cloud shows a sharp cloudbow indicative of large spherical droplets; the extensive tropical cirrus cloud shows no discrete features, and is readily differentiated from liquid-droplet clouds.

FIG. 14
FIG. 14

Polarization of the “earthshine” reflected back to the Earth by the Moon. The dark side of the Moon serves as a depolarizing “mirror” in which we view ourselves, providing a complete phase curve of the global Earth every 14 days. The polarization measurements of Dollfus27 (●) have been multiplied by 3.5 to correct for depolarization by the lunar surface. In addition are shown recent measurements of the global Earth from the Voyager 128 (○) and Pioneer Venus Obiter29 (+) space probes.

FIG. 15
FIG. 15

Surveyor III photographs of the Earth eclipsing the sun. One image is shown nested within the other. The refraction halo contains a number of bright beads, which correlate well with cloud-free regions on the Earth’s limb (after Shoemaker et al.30).

FIG. 16
FIG. 16

Phase curve of global Venus. The brightness is expressed in astronomical magnitudes after normalization to standard Sun-Venus and Earth-Venus distances. Observations made from the earth are compared with four cloud-model calculations (after Arking and Potter31).

FIG. 17
FIG. 17

Synthesis of ground-based observations of the polarization of sunlight reflected by Venus. The mean variation of the percent linear polarization is shown as a function of phase angle V and wavelength λ. The complex structure is fully understood in terms of molecular scattering plus multiple scatterinq by a cloud of spherical droplets (after Dollfus and Coffeen32).

FIG. 18
FIG. 18

Calculations of percent polarization for single scattering of unpolarized incident light by spheres of (real) refractive index 1.40. On the left are the wild fluctuations in polarization (black is positive polarization, implying electric vector vibration perpendicular to the plane of scattering- white is negative implying parallel) for a single particle of radius a. On the right are the same data but for a relatively narrow size distribution (effective variance = b = 0.01) having mean effective radius = a. Note that the integration over size eliminates the detailed interference patterns, revealing the features of cloudbow glory, etc. (after Hansen and Travis12).

FIG. 19
FIG. 19

Polarization of sunlight reflected by Venus in the ultraviolet. The ground-based data were obtained over a ten year period at observatories in the United States and France. The theoretical curves are for a homogeneous model containing spherical particles of refractive index 1.45 and mean radius 1.05 μm, with three different contributions by Rayleigh (gas) scattering. With no molecular scattering (fR = 0) the cloudbow and anomalous diffraction feature are reproduced well. But a moderate amount of Rayleigh scattering (fR = 0.045, corresponding to an atmospheric pressure of ∼50 mb at unit cloud optical depth) is required to match the observations at intermediate phase angles (after Hansen and Hovenier34).

FIG. 20
FIG. 20

Image of Venus taken 16 February 1979 by the spin-scan system on the Pioneer Venus Orbiter at 365 nm wavelength. The contrast, typically 30% or less, has been exaggerated in this display. The disk was almost fully illuminated, the phase angle being 13°. The cloud features evolve rapidly, and show an apparent rotation about the planet with a period of ∼4 days (see Travis et al.37).

FIG. 21
FIG. 21

Jupiter measurements along a north-south scan line at 103° phase angle taken by the Imaging Photopolarimeter on Pioneer 10. Illustrated are, starting from the bottom, the intensity at 440 nm, the color ratio (440/640), the percent linear polarization, and the direction of maximum vibration. The scan crossed various belts and zones as indicated. Note the Red Spot which is dark in the blue, the very large polarizations found at the limbs, the variability of Palong the scan, and the uniformity of θ (after Coffeen43).

FIG. 22
FIG. 22

Jupiter cloud-top altitudes (above the 650-mbar level) based on the observations in Fig. 21 and a simple model of gas above clouds. Note the height of the Red Spot above its surroundings (after Coffeen43).

PLATE 111
PLATE 111

(David L. Coffeen, p. 1051). Looking southwest from Puerto Peñasco, Mexico, across the Gulf of California, after sunset. This photograph was taken by the author in May 1967. Intense purple light covered most of the sky. It is tempting to associate this with stratospheric aerosols of volcanic origin. The Gunung Agung eruption, four years earlier, was followed almost immediately by a long period of remarkable sunsets. Several significant eruptions occurred throughout the world during the year before this photograph was taken.

PLATE 112
PLATE 112

(David L. Coffeen, p. 1051). Image of Jupiter taken 2 December 1974 by the spin-scan system on Pioneer 11, at a distance of 1.1 × 106 km. The morning terminator is on the left; the Great Red Spot is prominent in the South Tropical Zone. The various cloud species are as yet unidentified (after Fimmel, Swindell, and Burgess42).

Equations (2)

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intensity 1 λ 4 ( n 2 1 ) 2 1 6 + 3 δ 6 7 δ 1 + cos 2 θ 1 .
P = sin 2 θ 1 + cos 2 θ + [ 2 δ / ( 1 δ ) ] .