Abstract

A description is given of the design and construction of two instruments for studying atmospheric optics. One device, the Recording Polar Nephelometer, measures the volume scattering index of light passing through a sample of natural atmosphere, with scattering angle, polarization, and wavelength as variables. A new calibration procedure has been developed which employs a diffusing screen of known reflectance and transmittance as the standard. The second device, the Portable Transmissometer, measures the extinction coefficient with an accuracy of 5% under all conditions. These instruments are transported by a specially-equipped station wagon to form a mobile research unit. Samples of results obtained in fog and clear air are included.

© 1960 Optical Society of America

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References

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  1. W. E. K. Middelton, Vision Through the Atmosphere (University of Toronto Press, Toronto, Canada, 1952).
  2. F. Perrin, J. Chem. Phys. 10, 415 (1942).
    [CrossRef]
  3. R. Clark Jones, J. Opt. Soc. Am. 37, 107 (1947).
    [CrossRef]
  4. B. H. Billings and E. H. Land, J. Opt. Soc. Am. 38, 819 (1948).
    [CrossRef] [PubMed]
  5. G. G. Stokes, Trans. Cambridge Phil. Soc. 9, 399 (1852).
  6. J. M. Waldram, Trans. Illum. Eng. Soc. (London) 10, 147 (1945).
  7. B. H. Billings, J. Opt. Soc. Am. 41, 966 (1951).
    [CrossRef]
  8. B. S. Pritchard and G. W. Trytten, J. Opt. Soc. Am. 47, 118 (1957).
  9. Curcio, Drummeter, Petty, Stewart, and Butler, J. Opt. Soc. Am. 43, 97 (1953).
    [CrossRef]
  10. L. Foitzik, Wiss. Abhandl. Reichsamt Wetterdienst, Berlin 4, No. 5 (1938).
  11. H. S. Stewart and J. A. Curcio, J. Opt. Soc. Am. 42, 801 (1952).
    [CrossRef]
  12. Gumprecht, Sung, Chin, and Sliepcevich, J. Opt. Soc. Am. 42, 226 (1952).
    [CrossRef]

1957 (1)

B. S. Pritchard and G. W. Trytten, J. Opt. Soc. Am. 47, 118 (1957).

1953 (1)

1952 (2)

1951 (1)

1948 (1)

1947 (1)

1945 (1)

J. M. Waldram, Trans. Illum. Eng. Soc. (London) 10, 147 (1945).

1942 (1)

F. Perrin, J. Chem. Phys. 10, 415 (1942).
[CrossRef]

1938 (1)

L. Foitzik, Wiss. Abhandl. Reichsamt Wetterdienst, Berlin 4, No. 5 (1938).

1852 (1)

G. G. Stokes, Trans. Cambridge Phil. Soc. 9, 399 (1852).

Billings, B. H.

Butler,

Chin,

Clark Jones, R.

Curcio,

Curcio, J. A.

Drummeter,

Foitzik, L.

L. Foitzik, Wiss. Abhandl. Reichsamt Wetterdienst, Berlin 4, No. 5 (1938).

Gumprecht,

Land, E. H.

Middelton, W. E. K.

W. E. K. Middelton, Vision Through the Atmosphere (University of Toronto Press, Toronto, Canada, 1952).

Perrin, F.

F. Perrin, J. Chem. Phys. 10, 415 (1942).
[CrossRef]

Petty,

Pritchard, B. S.

B. S. Pritchard and G. W. Trytten, J. Opt. Soc. Am. 47, 118 (1957).

Sliepcevich,

Stewart,

Stewart, H. S.

Stokes, G. G.

G. G. Stokes, Trans. Cambridge Phil. Soc. 9, 399 (1852).

Sung,

Trytten, G. W.

B. S. Pritchard and G. W. Trytten, J. Opt. Soc. Am. 47, 118 (1957).

Waldram, J. M.

J. M. Waldram, Trans. Illum. Eng. Soc. (London) 10, 147 (1945).

J. Chem. Phys. (1)

F. Perrin, J. Chem. Phys. 10, 415 (1942).
[CrossRef]

J. Opt. Soc. Am. (7)

Trans. Cambridge Phil. Soc. (1)

G. G. Stokes, Trans. Cambridge Phil. Soc. 9, 399 (1852).

Trans. Illum. Eng. Soc. (London) (1)

J. M. Waldram, Trans. Illum. Eng. Soc. (London) 10, 147 (1945).

Wiss. Abhandl. Reichsamt Wetterdienst, Berlin (1)

L. Foitzik, Wiss. Abhandl. Reichsamt Wetterdienst, Berlin 4, No. 5 (1938).

Other (1)

W. E. K. Middelton, Vision Through the Atmosphere (University of Toronto Press, Toronto, Canada, 1952).

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Figures (13)

Fig. 1
Fig. 1

Recording Polar Nephelometer.

Fig. 2
Fig. 2

Recording Polar Nephelometer optical schematic.

Fig. 3
Fig. 3

Recording Polar Nephelometer light trap.

Fig. 4
Fig. 4

Recording Polar Nephelometer block diagram.

Fig. 5
Fig. 5

Portable Transmissometer. The projector, battery, and current regulator are on the left; the receiver and alternative types of photometers on the right.

Fig. 6
Fig. 6

Portable Transmissometer projector optical schematic.

Fig. 7
Fig. 7

Mobile measuring station. The Recording Polar Nephelometer and Portable Transmissometer are transported in a modified station wagon. A gasoline-driven generator carried in the trailer furnishes 110-v, 60-cy power. Communication is maintained among the units in the field via FM radio. The Recording Polar Nephelometer with a sunshade is set up near the door of the wagon and the transmissometer units and radios are at either side.

Fig. 8
Fig. 8

Interior of station wagon. An FM transceiver (upper left), controls for the Recording Polar Nephelometer (lower left), and the recorder (right) are mounted just behind the front seat of the station wagon.

Fig. 9
Fig. 9

Polar scattering diagrams for a clear night, March 13, 1957, 11:00 p.m. near Dexter, Michigan. The green color filter and aperture set B were employed. σ=4.9×10−5, b=2.6×10−5, and k=2.3×10−5 ft−1. D2 was 11.2 miles and D1 was 142.8 ft. The temperature was 53°F, the relative humidity 35%, and the meteorological range 15 miles.

Fig. 10
Fig. 10

Normalized matrix coefficients derived from data in Fig. 9.

Fig. 11
Fig. 11

Five additional types of scattering diagrams computed from coefficients in Fig. 10.

Fig. 12
Fig. 12

Polar scattering diagrams for the same situation as Fig. 911, but for red and blue light. For blue, σ=6.1×10−5, b=3.7×1−5, and k=2.4×10−5 ft−1. For red, σ=4.8×10−5, b=2.1×10−5, and k=2.7×10−5 ft−1.

Fig. 13
Fig. 13

Polar scattering diagrams for fog, February 26, 1957, 6:00 a.m., near Ann Arbor, Michigan. The green filter and aperture set B were used. The meteorological range was 1670 ft and σ=2.34×10−3 ft−1 on the basis of the assumption that k was negligible.

Tables (1)

Tables Icon

Table I Tabulated values of the unpolarized scattering index for red, green, and blue light computed from the measurements shown in Fig. 9 and 12.

Equations (69)

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T = P / P 0 .
T = e - σ D ,
V = 3.912 / σ .
σ = b + k .
d J = β H d v ,
b = 2 π 0 π β U U sin ϕ d ϕ ,
T = F / F 0 ,
d I = β E d v .
| a 1 b 1 0 0 b 1 a 2 0 0 0 0 a 3 b 2 0 0 - b 2 a 4 |
a 1     | 1.00 b 1 0 0 b 1 a 2 0 0 0 0 a 3 b 2 0 0 - b 2 a 4 | ,
a 2 = a 2 / a 1 ,
a 3 = a 3 / a 1 ,
a 4 = a 4 / a 1 ,
b 1 = b 1 / a 1 ,
b 2 = b 2 / a 1 .
| a 1 0 0 0 0 0 a 2 0 0 0 0 0 a 2 0 0 0 0 0 a 4 0 |
| a 1 π 0 0 0 0 a 2 π 0 0 0 0 - a 2 π 0 0 0 0 a 4 π | .
a 1 = a 2
a 3 = a 4 .
| a 1 0 0 0 0 0 a 1 0 0 0 0 0 a 1 0 0 0 0 0 a 1 0 | ,
| a 1 π 0 0 0 0 a 1 π 0 0 0 0 - a 1 π 0 0 0 0 - a 1 π | .
a 1 = 1 2 β H H + 1 2 β V V + β H V = β U U ,
a 2 = 1 2 β H H + 1 2 β V V - β H V ,
a 3 = 2 β D D - a 1 ,
a 4 = 2 β R R - a 1 ,
b 1 = 1 2 β H H - 1 2 β V V ,
b 2 = a 1 - 2 β D R .
β H H = 1 2 ( a 1 + a 2 ) + b 1 ,
β V V = 1 2 ( a 1 + a 2 ) - b 1 ,
β H V = β V H = 1 2 ( a 1 - a 2 ) ,
β D D = β d d = 1 2 ( a 1 + a 3 ) ,
β D d = β d D = 1 2 ( a 1 - a 3 ) ,
β R R = β L L = 1 2 ( a 1 + a 4 ) ,
β R L = β L R = 1 2 ( a 1 - a 4 ) ,
β R D = β d R = β L d = β D L = 1 2 ( a 1 + b 2 ) ,
β D R = β R d = β L D = β d L = 1 2 ( a 1 - b 2 ) ,
β H D = β H d = β H R = β H L = β D H = β d H = β R H = β L H = 1 2 ( a 1 + b 1 ) ,
β V D = β V d = β V R = β V L = β D V = β d V = β R V = β L V = 1 2 ( a 1 - b 1 ) .
F β v B S T P T R A P A R / D 4 ,
B c = R E cos γ / π ,
d I c = B c cos γ d A ,
d F c = C 1 d I c .
d W c = C 2 d F c .
d W c = R cos γ cos γ C 1 C 2 E d A / π .
W c = R cos γ cos γ π A C 1 C 2 E d A .
x W c d x = R cos γ cos γ π x A C 1 C 2 E d A d x .
x W c d x = R cos γ cos γ π C 1 C 2 E d v .
d I a = β ( ϕ ) E d v .
d F a = C 1 d I a .
d W a = C 2 d F a .
d W a = C 1 C 2 E β d v .
W a = β v C 1 C 2 E d v .
β = R cos γ cos γ π W a W c d x
β = K W a ,
K = R cos γ cos γ π W c d x .
W c d x = R cos γ cos γ C 1 C 2 E v / π .
K = 1 / C 1 C 2 E v .
R U U = π B U / E U ,
β U U = d I U / E U d v ,
R P P = π B P / E P .
β P P = d I P / E P d v ,
| 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 |
| 0.98 0 0 0 0 0.10 0 0 0 0 - 0.10 0 0 0 0 - 0.03 | .
T 2 - 1 = w 2 t 1 D 2 2 / w 1 t 2 D 1 2 ,
σ = - ln T 2 - 1 / ( D 2 - D 1 ) .
β = ϕ T W a / ϕ c π W c d x .
s ( T 1 - 2 ) = π 2 θ R θ P β U U ( 0 ) ( D 2 - D 1 ) ,
s ( σ ) = - π θ R θ P β U U ( 0 ) 2 σ .
w ( σ ) = w ( T 1 - 2 ) / ( D 2 - D 1 ) σ .