Abstract

Superior mirages of simple appearance are occasionally observed over distances exceeding 70 km. These mirages cannot be explained in terms of standard textbook models; rather, they are shown to arise from fairly complex atmospheres. Two observations of different types, observed at Resolute Bay, Canada, are presented. The first is the basic three-image mirage in which one inverted and one erect image float above the object. The second is a single-image mirage in which the object is elevated but undistorted. For each, the most suitable atmospheric model contains several distinct atmospheres, and the first one requires sloped atmospheric layers as well.

© 1998 Optical Society of America

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References

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  1. S. W. Visser, “The Novaya Zemlya phenomenon,” Proc. K. Ned. Akad. Wet. Ser. B 59, 375–385 (1956).
  2. W. H. Lehn, “The Novaya Zemlya effect: an arctic mirage,” J. Opt. Soc. Am. 69, 776–781 (1979).
    [CrossRef]
  3. M. G. J. Minnaert, Light and Color in the Outdoors (Springer-Verlag, New York, 1993), p. 72.
  4. W. J. Humphreys, Physics of the Air, 3rd ed. (Dover, New York, 1964), p. 472.
  5. J. M. Pernter, F. Exner, Meteorologische Optik, 2nd ed. (Braumüller, Vienna, 1922), pp. 110ff, p. 125.
  6. F. W. Sears, Optics, 3rd ed. (Addison-Wesley, Cambridge, Mass., 1949), p. 7 (looming).
  7. Ref. 5, pp. 84ff (Erhebung).
  8. Ref. 3, p. 61.
  9. The map was obtained from a website entitled “Online Map Creation,” at www.aquarius.geomar.de .
  10. U.S. Standard Atmosphere, 1976, in R. G. Fleagle, J. A. Businger, Introduction to Atmospheric Physics, 2nd ed. (Academic, New York, 1980), p. 415.
  11. W. H. Lehn, W. Friesen, “Simulation of mirages,” Appl. Opt. 31, 1267–1273 (1992).
    [CrossRef] [PubMed]
  12. Ref. 5, p. 109.
  13. T. L. Legal, “Modelling of sloped atmosphere mirages,” M.Sc. thesis (University of Manitoba, Winnipeg, Canada, 1995).
  14. S. R. Church, “Atmospheric mirage and distortion modeling for IR target injection simulations,” in Targets and Backgrounds: Characterization and Representation II, W. R. Watkins, D. Clement, eds., Proc. SPIE2742, 122–135 (1996).
    [CrossRef]

1992

1979

1956

S. W. Visser, “The Novaya Zemlya phenomenon,” Proc. K. Ned. Akad. Wet. Ser. B 59, 375–385 (1956).

Businger, J. A.

U.S. Standard Atmosphere, 1976, in R. G. Fleagle, J. A. Businger, Introduction to Atmospheric Physics, 2nd ed. (Academic, New York, 1980), p. 415.

Church, S. R.

S. R. Church, “Atmospheric mirage and distortion modeling for IR target injection simulations,” in Targets and Backgrounds: Characterization and Representation II, W. R. Watkins, D. Clement, eds., Proc. SPIE2742, 122–135 (1996).
[CrossRef]

Exner, F.

J. M. Pernter, F. Exner, Meteorologische Optik, 2nd ed. (Braumüller, Vienna, 1922), pp. 110ff, p. 125.

Fleagle, R. G.

U.S. Standard Atmosphere, 1976, in R. G. Fleagle, J. A. Businger, Introduction to Atmospheric Physics, 2nd ed. (Academic, New York, 1980), p. 415.

Friesen, W.

Humphreys, W. J.

W. J. Humphreys, Physics of the Air, 3rd ed. (Dover, New York, 1964), p. 472.

Legal, T. L.

T. L. Legal, “Modelling of sloped atmosphere mirages,” M.Sc. thesis (University of Manitoba, Winnipeg, Canada, 1995).

Lehn, W. H.

Minnaert, M. G. J.

M. G. J. Minnaert, Light and Color in the Outdoors (Springer-Verlag, New York, 1993), p. 72.

Pernter, J. M.

J. M. Pernter, F. Exner, Meteorologische Optik, 2nd ed. (Braumüller, Vienna, 1922), pp. 110ff, p. 125.

Sears, F. W.

F. W. Sears, Optics, 3rd ed. (Addison-Wesley, Cambridge, Mass., 1949), p. 7 (looming).

Visser, S. W.

S. W. Visser, “The Novaya Zemlya phenomenon,” Proc. K. Ned. Akad. Wet. Ser. B 59, 375–385 (1956).

Appl. Opt.

J. Opt. Soc. Am.

Proc. K. Ned. Akad. Wet. Ser. B

S. W. Visser, “The Novaya Zemlya phenomenon,” Proc. K. Ned. Akad. Wet. Ser. B 59, 375–385 (1956).

Other

Ref. 5, p. 109.

T. L. Legal, “Modelling of sloped atmosphere mirages,” M.Sc. thesis (University of Manitoba, Winnipeg, Canada, 1995).

S. R. Church, “Atmospheric mirage and distortion modeling for IR target injection simulations,” in Targets and Backgrounds: Characterization and Representation II, W. R. Watkins, D. Clement, eds., Proc. SPIE2742, 122–135 (1996).
[CrossRef]

M. G. J. Minnaert, Light and Color in the Outdoors (Springer-Verlag, New York, 1993), p. 72.

W. J. Humphreys, Physics of the Air, 3rd ed. (Dover, New York, 1964), p. 472.

J. M. Pernter, F. Exner, Meteorologische Optik, 2nd ed. (Braumüller, Vienna, 1922), pp. 110ff, p. 125.

F. W. Sears, Optics, 3rd ed. (Addison-Wesley, Cambridge, Mass., 1949), p. 7 (looming).

Ref. 5, pp. 84ff (Erhebung).

Ref. 3, p. 61.

The map was obtained from a website entitled “Online Map Creation,” at www.aquarius.geomar.de .

U.S. Standard Atmosphere, 1976, in R. G. Fleagle, J. A. Businger, Introduction to Atmospheric Physics, 2nd ed. (Academic, New York, 1980), p. 415.

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Figures (10)

Fig. 1
Fig. 1

(a) Normal view of the Somerset peaks from a distance of 19 km, (b) superior mirage from 77.7 km. The peaks look smaller in (b) because the intervening ice horizon cuts off the lower portion of the image.

Fig. 2
Fig. 2

Geographic profile with flattened Earth and magnified vertical scale. Regions I and II apply to the third model for the Somerset mirage.

Fig. 3
Fig. 3

Map of the Resolute region. The letters C and S on the line of sight to Bathurst Island identify Claxton Point and Sheringham Point, respectively.

Fig. 4
Fig. 4

Temperature profiles. Curves 1 and 2 represent models 1 and 2 of the Somerset mirage. The curve for model 2, the sloped atmosphere, represents the profile at the distance of 77.7 km from the observer. Straight line 3, which has a lapse rate of 6.5°/km, gives the standard atmosphere10 for comparison. Curve 4 is the profile measured by the AES.

Fig. 5
Fig. 5

(a) Temperature profiles for model 3: near atmosphere (solid curve 1), far atmosphere (dotted curve 2), standard atmosphere for comparison (dashed curve 3); (b) ray paths; (c) mirage simulation.

Fig. 6
Fig. 6

(a) Bathurst Island mirage, (b) measured elevation angles of the mirage image.

Fig. 7
Fig. 7

Bathurst peak at a distance of 106 km, as seen from a hill of 171-m height at Resolute. To make the peak more visible, contrast has been enhanced and the peak has been outlined with dots.

Fig. 8
Fig. 8

Geographic profile for the Bathurst observation. Ray 1 is the horizon ray, with an elevation angle of -14.2 arc min at the observer. This ray clears Sheringham Point (marked S) but is interrupted by Claxton Point (C). The lowest ray, 2, to clear Claxton Point has an elevation of -12.6 arc min. In a standard atmosphere it passes well above the Bathurst peak. The dashed lines indicate the average height and the extent of the inversions used in models 1 and 2.

Fig. 9
Fig. 9

Temperature profiles for the Bathurst mirage models. Curve 1 is the weak low-level inversion of model 1, lying just beyond Claxton Point. Curve 2 represents the sloping inversion of model 2 as it would appear at the Bathurst peak.

Fig. 10
Fig. 10

Selected rays for model 1 of the Bathurst mirage. Ray elevation angles at the eye have the values of -12.5 to -9.5 arc min in 1-arc min intervals. The inversion, indicated by the dotted area, is centered on a 60-m elevation and extends from 32 to 68 km. In this region the flattening of the rays can be seen, as the inversion tries to straighten them.

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