Abstract

Grandmontagne and later Vaucouleurs have observed discontinuities in the slope of the zenith-sky brightness curve during twilight at solar depressions of about 6°, 9°, 10°, and 12°, which are explained to be due to separate diffusing and luminescent layers in the upper atmosphere. No such evidence is, however, found by Koomen and co-workers in their recent photoelectric measurements in the United States.

The effect of a possible discontinuity could be enhanced by observing the difference in radiance of two similar patches of the zenith sky in the sun’s meridian, this being more susceptible to changes accompanying the crossing of a layer by the earth’s shadow. Observations on very clear days with a photoelectric differential twilight photometer recording this difference through three narrow-band interference filters have not disclosed any evidence of the discontinuities, the recorded curves running perfectly smooth till the end of astronomical twilight. From estimates of the least radiant energy which the photometer could detect, the possibility of detecting a layer of scattering material at the heights of the reported discontinuities is discussed.

© 1955 Optical Society of America

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References

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  1. R. Grandmontagne, Ann. phys. 16, 253 (1941).
  2. J. Gauzit and R. Grandmontagne, Comptes rend. 214, 799 (1942).
  3. F. Link, Bull. Ast. Inst. Czechoslovakia 1, 137 (1949).
  4. R. Grandmontagne, Comptes rend. 236, 1066 (1953).
  5. H. C. van de Hulst, The Atmospheres of the Earth and Planets, edited by G. P. Kuiper (University of Chicago Press, Chicago, 1952) 2nd Ed., Ch. III, p. 84.
  6. G. Vaucouleurs, Comptes rend. 232, 342 (1951).
  7. Koomen, Lock, Packer, Scolnik, Tousey, and Hulburt, J. Opt. Soc. Am. 42, 353 (1952); Mém. soc. roy. sci. Liège 12, 135 (1952).
    [CrossRef]
  8. E. O. Hulburt, J. Opt. Soc. Am. 28, 227 (1938).
    [CrossRef]
  9. E. O. Hulburt, J. Opt. Soc. Am. 43, 113 (1953).
    [CrossRef]
  10. Tables of Scattering Functions for Spherical Particles, Natl. Bur. of Standards, Appl. Math. Series-4 (U. S. Government Printing Office, Washington, D. C., 1948).
  11. R. O. Gumprecht and C. M. Sliepcevich, Tables of Light Scattering Functions for Spherical Particles [University of Michigan, Engineering Research Institute, Special Publication, Michigan, (1951)].
  12. Gumprecht, Sung, Chin, and Sliepcevich, J. Opt. Soc. Am. 42, 226 (1952).
    [CrossRef]
  13. R. Tousey, private communication.
  14. R. Stair, J. Research Natl. Bur. Standards 49, 227 (1952).
    [CrossRef]
  15. Havens, Koll, and LaGow, J. Geophys. Research 57, 59 (1952).
    [CrossRef]
  16. F. L. Whipple, Advances in Geophysics, Vol. I, edited by H. E. Landsberg (Academic Press, Inc., New York, 1952) p. 131–133 and references quoted there.

1953 (2)

R. Grandmontagne, Comptes rend. 236, 1066 (1953).

E. O. Hulburt, J. Opt. Soc. Am. 43, 113 (1953).
[CrossRef]

1952 (4)

1951 (1)

G. Vaucouleurs, Comptes rend. 232, 342 (1951).

1949 (1)

F. Link, Bull. Ast. Inst. Czechoslovakia 1, 137 (1949).

1942 (1)

J. Gauzit and R. Grandmontagne, Comptes rend. 214, 799 (1942).

1941 (1)

R. Grandmontagne, Ann. phys. 16, 253 (1941).

1938 (1)

Chin,

Gauzit, J.

J. Gauzit and R. Grandmontagne, Comptes rend. 214, 799 (1942).

Grandmontagne, R.

R. Grandmontagne, Comptes rend. 236, 1066 (1953).

J. Gauzit and R. Grandmontagne, Comptes rend. 214, 799 (1942).

R. Grandmontagne, Ann. phys. 16, 253 (1941).

Gumprecht,

Gumprecht, R. O.

R. O. Gumprecht and C. M. Sliepcevich, Tables of Light Scattering Functions for Spherical Particles [University of Michigan, Engineering Research Institute, Special Publication, Michigan, (1951)].

Havens,

Havens, Koll, and LaGow, J. Geophys. Research 57, 59 (1952).
[CrossRef]

Hulburt,

Hulburt, E. O.

Koll,

Havens, Koll, and LaGow, J. Geophys. Research 57, 59 (1952).
[CrossRef]

Koomen,

LaGow,

Havens, Koll, and LaGow, J. Geophys. Research 57, 59 (1952).
[CrossRef]

Link, F.

F. Link, Bull. Ast. Inst. Czechoslovakia 1, 137 (1949).

Lock,

Packer,

Scolnik,

Sliepcevich,

Sliepcevich, C. M.

R. O. Gumprecht and C. M. Sliepcevich, Tables of Light Scattering Functions for Spherical Particles [University of Michigan, Engineering Research Institute, Special Publication, Michigan, (1951)].

Stair, R.

R. Stair, J. Research Natl. Bur. Standards 49, 227 (1952).
[CrossRef]

Sung,

Tousey,

Tousey, R.

R. Tousey, private communication.

van de Hulst, H. C.

H. C. van de Hulst, The Atmospheres of the Earth and Planets, edited by G. P. Kuiper (University of Chicago Press, Chicago, 1952) 2nd Ed., Ch. III, p. 84.

Vaucouleurs, G.

G. Vaucouleurs, Comptes rend. 232, 342 (1951).

Whipple, F. L.

F. L. Whipple, Advances in Geophysics, Vol. I, edited by H. E. Landsberg (Academic Press, Inc., New York, 1952) p. 131–133 and references quoted there.

Ann. phys. (1)

R. Grandmontagne, Ann. phys. 16, 253 (1941).

Bull. Ast. Inst. Czechoslovakia (1)

F. Link, Bull. Ast. Inst. Czechoslovakia 1, 137 (1949).

Comptes rend. (3)

R. Grandmontagne, Comptes rend. 236, 1066 (1953).

J. Gauzit and R. Grandmontagne, Comptes rend. 214, 799 (1942).

G. Vaucouleurs, Comptes rend. 232, 342 (1951).

J. Geophys. Research (1)

Havens, Koll, and LaGow, J. Geophys. Research 57, 59 (1952).
[CrossRef]

J. Opt. Soc. Am. (4)

J. Research Natl. Bur. Standards (1)

R. Stair, J. Research Natl. Bur. Standards 49, 227 (1952).
[CrossRef]

Other (5)

F. L. Whipple, Advances in Geophysics, Vol. I, edited by H. E. Landsberg (Academic Press, Inc., New York, 1952) p. 131–133 and references quoted there.

Tables of Scattering Functions for Spherical Particles, Natl. Bur. of Standards, Appl. Math. Series-4 (U. S. Government Printing Office, Washington, D. C., 1948).

R. O. Gumprecht and C. M. Sliepcevich, Tables of Light Scattering Functions for Spherical Particles [University of Michigan, Engineering Research Institute, Special Publication, Michigan, (1951)].

R. Tousey, private communication.

H. C. van de Hulst, The Atmospheres of the Earth and Planets, edited by G. P. Kuiper (University of Chicago Press, Chicago, 1952) 2nd Ed., Ch. III, p. 84.

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Figures (3)

Fig. 1
Fig. 1

Principle of the observation of a discontinuity in the radiance of the twilight sky.

Fig. 2
Fig. 2

Differential twilight photometer.

Fig. 3
Fig. 3

A typical curve of (N2N1) obtained during twilight at Ottawa.

Tables (1)

Tables Icon

Table I Estimates of detectable scattering material at the heights of the postulated discontinuities. Filter used: 460 mμ

Equations (1)

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H 0 λ · exp ( - β λ N ¯ ) · ( λ 2 / 8 π 2 ) ( i 1 + i 2 ) γ · x × exp [ - B λ h ( n 0 - n ) ] = δ N .