Abstract

Zenith sky brightness at totality was observed to be about four orders of magnitude lower than that for a normal day sky. The spectral distributions in terms of an effective blackbody temperature for the range 4100–8000 Å were 5000 K, 9000 K, and 11,000 K for the twilight, control day sky, and totality, respectively, indicating a shift toward the shorter wavelength at totality. The polarization measured in the sun’s vertical plane 90° away from the sun was 4% and 0.6% at 4750 Å and 6000 Å, respectively. Both colors showed a change in the plane of polarization of about 50° at the time of totality. From the change in the plane of polarization it is estimated from the primary component reduced by about an order of magnitude at totality of the eclipse.

© 1971 Optical Society of America

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References

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  1. B. S. Dandekar, Appl. Opt. 7, 705 (1968).
    [CrossRef] [PubMed]
  2. W. E. Sharp, J. W. F. Lloyd, S. Silverman, Appl. Opt. 10, 1207 (1971).
    [CrossRef] [PubMed]
  3. K. L. Coulson, J. V. Dave, Z. Sekera, Tables Related to Radiation Emerging from a Planetary Atmosphere with Rayleigh Scattering (University of California Press, Berkeley and Los Angeles, 1960).
  4. J. V. Dave, J. Opt. Soc. Amer. 54, 307 (1964).
    [CrossRef]
  5. E. de Bary, K. Bullrich, J. Opt. Soc. Amer. 54, 1413 (1964).
    [CrossRef]
  6. E. de Bary, Appl. Opt. 3, 1293 (1964).
    [CrossRef]
  7. E. de Bary, K. Bullrich, D. Lorenz, Geofis. Pura Appl. 48, 193 (1961).
    [CrossRef]
  8. J. G. Moore, C. R. N. Rao, Ann. Geophys. 22, 147 (1966).
  9. J. G. Moore, C. R. N. Rao, “Photometry of the Daytime Sky during Total Solar Eclipses,” presented at Eclipse Symposium, Brazil (1967).

1971 (1)

1968 (1)

1966 (1)

J. G. Moore, C. R. N. Rao, Ann. Geophys. 22, 147 (1966).

1964 (3)

J. V. Dave, J. Opt. Soc. Amer. 54, 307 (1964).
[CrossRef]

E. de Bary, K. Bullrich, J. Opt. Soc. Amer. 54, 1413 (1964).
[CrossRef]

E. de Bary, Appl. Opt. 3, 1293 (1964).
[CrossRef]

1961 (1)

E. de Bary, K. Bullrich, D. Lorenz, Geofis. Pura Appl. 48, 193 (1961).
[CrossRef]

Bullrich, K.

E. de Bary, K. Bullrich, J. Opt. Soc. Amer. 54, 1413 (1964).
[CrossRef]

E. de Bary, K. Bullrich, D. Lorenz, Geofis. Pura Appl. 48, 193 (1961).
[CrossRef]

Coulson, K. L.

K. L. Coulson, J. V. Dave, Z. Sekera, Tables Related to Radiation Emerging from a Planetary Atmosphere with Rayleigh Scattering (University of California Press, Berkeley and Los Angeles, 1960).

Dandekar, B. S.

Dave, J. V.

J. V. Dave, J. Opt. Soc. Amer. 54, 307 (1964).
[CrossRef]

K. L. Coulson, J. V. Dave, Z. Sekera, Tables Related to Radiation Emerging from a Planetary Atmosphere with Rayleigh Scattering (University of California Press, Berkeley and Los Angeles, 1960).

de Bary, E.

E. de Bary, K. Bullrich, J. Opt. Soc. Amer. 54, 1413 (1964).
[CrossRef]

E. de Bary, Appl. Opt. 3, 1293 (1964).
[CrossRef]

E. de Bary, K. Bullrich, D. Lorenz, Geofis. Pura Appl. 48, 193 (1961).
[CrossRef]

Lloyd, J. W. F.

Lorenz, D.

E. de Bary, K. Bullrich, D. Lorenz, Geofis. Pura Appl. 48, 193 (1961).
[CrossRef]

Moore, J. G.

J. G. Moore, C. R. N. Rao, Ann. Geophys. 22, 147 (1966).

J. G. Moore, C. R. N. Rao, “Photometry of the Daytime Sky during Total Solar Eclipses,” presented at Eclipse Symposium, Brazil (1967).

Rao, C. R. N.

J. G. Moore, C. R. N. Rao, Ann. Geophys. 22, 147 (1966).

J. G. Moore, C. R. N. Rao, “Photometry of the Daytime Sky during Total Solar Eclipses,” presented at Eclipse Symposium, Brazil (1967).

Sekera, Z.

K. L. Coulson, J. V. Dave, Z. Sekera, Tables Related to Radiation Emerging from a Planetary Atmosphere with Rayleigh Scattering (University of California Press, Berkeley and Los Angeles, 1960).

Sharp, W. E.

Silverman, S.

Ann. Geophys. (1)

J. G. Moore, C. R. N. Rao, Ann. Geophys. 22, 147 (1966).

Appl. Opt. (3)

Geofis. Pura Appl. (1)

E. de Bary, K. Bullrich, D. Lorenz, Geofis. Pura Appl. 48, 193 (1961).
[CrossRef]

J. Opt. Soc. Amer. (2)

J. V. Dave, J. Opt. Soc. Amer. 54, 307 (1964).
[CrossRef]

E. de Bary, K. Bullrich, J. Opt. Soc. Amer. 54, 1413 (1964).
[CrossRef]

Other (2)

K. L. Coulson, J. V. Dave, Z. Sekera, Tables Related to Radiation Emerging from a Planetary Atmosphere with Rayleigh Scattering (University of California Press, Berkeley and Los Angeles, 1960).

J. G. Moore, C. R. N. Rao, “Photometry of the Daytime Sky during Total Solar Eclipses,” presented at Eclipse Symposium, Brazil (1967).

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Figures (5)

Fig. 1
Fig. 1

Zenith sky brightness in rayleigh angstrom−1 for the continuum at 4200 Å, 5600 Å, 6300 Å, 7400 Å, and 8100 Å for a normal day sky and during totality.

Fig. 2
Fig. 2

Spectral distribution of the sky brightness normalized with respect to 6300 Å, for totality, normal day: (a) control-1 (7 March 1970, solar elevation 49°), (b) control-2 (6 March 1970, solar elevation 46°), and twilight. The respective blackbody temperatures are 11,000 K, 9700 K, 8900 K, and 5000 K.

Fig. 3
Fig. 3

Two scattered components Imax and Imin at solar azimuth 180° and a distance 90° away from the sun, at 4750 Å and 600 Å.

Fig. 4
Fig. 4

Percent polarization of sky brightness along the sun’s vertical at a distance 90° away from the sun, at 4750 Å and 6000 Å.

Fig. 5
Fig. 5

Change in the plane of polarization at 4750 Å and 6000 Å.

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