Abstract

We use Fraunhofer diffraction theory and meterological data to determine the nature of cloud-particle distributions and the mean particle sizes required for interpreting photographs of coronas and iridescence in mountain wave clouds. Traditional descriptions of coronas and iridescence usually explain these optical phenomena as diffraction by droplets of liquid water. Our analysis shows that the photographed displays have mean particle sizes from 7.6 to 24.3 μm, with over half the cases requiring diffraction by small (∼20 μm) quasispherical ice particles rather than liquid water droplets. Previous documentation of coronas produced by ice particles are limited to observations in cirrus clouds that appear to be composed of small ice crystals, whereas our observations suggest that coronas and iridescence quite often can be created by tiny quasispherical ice particles that might be unique to mountain wave clouds. Furthermore, we see that the dominant colors in mountain wave-cloud coronas are red and blue, rather than the traditionally described red and green.

© 2003 Optical Society of America

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References

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  1. G. C. Simpson, “Coronae and iridescent clouds,” Q. J. R. Meteorol. Soc. 38, 291–299 (1912).
    [CrossRef]
  2. K. Sassen, “Iridescence in an aircraft contrail,” J. Opt. Soc. Am. 69, 1080–1084 (1979).
    [CrossRef]
  3. J. A. Lock, L. Yang, “Mie theory of the corona,” Appl. Opt. 30, 3408–3414 (1991).
    [CrossRef] [PubMed]
  4. K. Sassen, “Corona-producing cirrus cloud properties derived from polarization lidar and photographic analyses,” Appl. Opt. 30, 3421–3428 (1991).
    [CrossRef] [PubMed]
  5. K. Sassen, G. G. Mace, J. Hallett, M. R. Poellot, “Corona-producing ice clouds: a case study of a cold mid-latitude cirrus layer,” Appl. Opt. 37, 1477–1485 (1998).
    [CrossRef]
  6. J. A. Shaw, “The Christmas corona,” Opt. Photon. News (April1997), pp. 52–53.
  7. S. D. Gedzelman, J. A. Lock, “Simulating coronas in color,” Appl. Opt. 42, 497–504 (2003).
    [CrossRef] [PubMed]
  8. R. B. Smith, “The influence of the mountains on the atmosphere,” in Advances in Geophysics, B. Saltzman, ed. (Academic, New York, 1979), vol. 21, pp. 87–230.
    [CrossRef]
  9. D. R. Durran, Mesoscale Meteorology and Forecasting, P.S. Ray, ed. (American Meteorological Society, Boston, 1986), pp. 472–492.
  10. T. Q. Carney, A. J. Bedard, J. M. Brown, J. McGinley, T. Lindholm, M. J. Kraus, Hazardous Mountain Winds and Their Visual Indicators, NOAA Handbook (Environmental Research Laboratories, Boulder, Colo., 1996).
  11. F. M. Ralph, P. J. Neiman, T. L. Keller, D. Levinson, L. S. Fedor, “Observations, simulations, and analysis of nonstationary trapped lee waves,” J. Atmos. Sci. 54, 1308–1333 (1997).
    [CrossRef]
  12. C. D. Whiteman, Mountain Meteorology: Fundamentals and Applications (Oxford U. Press, New York, 2000).
  13. H. R. Pruppacher, J. D. Klett, Microphysics of Clouds and Precipitation (Reidel, Boston, 1980).
  14. A. J. Heymsfield, L. M. Miloshevich, “Homogeneous nucleation and supercooled liquid water in orographic wave clouds,” J. Atmos. Sci. 50, 2335–2353 (1993).
    [CrossRef]
  15. A. J. Heymsfield, L. M. Miloshevich, “Relative humidity and temperature influences on cirrus formation and evolution: observations from wave clouds and FIRE II,” J. Atmos. Sci. 52, 4302–4326 (1995).
    [CrossRef]
  16. H. Gerber, C. H. Twohy, B. Gandrud, A. J. Heymsfield, G. M. McFarquhar, P. J. DeMott, D. C. Rogers, “Measurements of wave-cloud microphysical properties with two new aircraft probes,” Geophys. Res. Lett. 25, 1117–1120 (1998).
    [CrossRef]
  17. A. Heymsfield, Mesoscale and Microscale Meteorology Division, National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, Colo. 80301 (personal communication, 2001).
  18. C. F. Bohren, D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, New York, 1983).
  19. J. W. Goodman, Introduction to Fourier Optics, 2nd ed. (McGraw-Hill, New York, 1996).
  20. P. Queney, “The problem of airflow over mountains: a summary of theoretical studies,” Bull. Am. Meteorol. Soc. 29, 16–26 (1948).
  21. A. J. Heymsfield, C. M. R. Platt, “Parameterization of the particle size spectrum of ice clouds in terms of the ambient temperature and ice water content,” J. Atmos. Sci. 41, 846–855 (1984).
    [CrossRef]
  22. C. M. R. Platt, J. D. Spinhirne, W. D. Hart, “Optical and microphysical properties of a cold cirrus cloud: evidence for regions of small ice particles,” J. Geophys. Res. 94, 11151–11164 (1989).
    [CrossRef]
  23. K. Sassen, D. O. Starr, T. Uttal, “Mesoscale and microscale structure of cirrus clouds: three case studies,” J. Atmos. Sci. 46, 371–386 (1989).
    [CrossRef]
  24. J. Appleman, “The formation of exhaust condensation trails by jet aircraft,” Bull. Am. Meteorol. Soc. 34, 14–20 (1953).
  25. P. Parviainen, C. F. Bohren, V. Makela, “Vertical elliptial coronas caused by pollen,” Appl. Opt. 33, 4548–4554 (1994).
    [CrossRef] [PubMed]
  26. E. Trankle, B. Mielke, “Simulation and analysis of pollen coronas,” Appl. Opt. 33, 4552–4562 (1994).
    [CrossRef] [PubMed]
  27. F. M. Mims, “Solar corona caused by juniper pollen in Texas,” Appl. Opt. 37, 1486–1488 (1998).
    [CrossRef]
  28. P. J. Neiman, J. A. Shaw are preparing a manuscript to be called “Optical diffraction patterns in mountain wave clouds over northeastern Colorado.”

2003

1998

H. Gerber, C. H. Twohy, B. Gandrud, A. J. Heymsfield, G. M. McFarquhar, P. J. DeMott, D. C. Rogers, “Measurements of wave-cloud microphysical properties with two new aircraft probes,” Geophys. Res. Lett. 25, 1117–1120 (1998).
[CrossRef]

K. Sassen, G. G. Mace, J. Hallett, M. R. Poellot, “Corona-producing ice clouds: a case study of a cold mid-latitude cirrus layer,” Appl. Opt. 37, 1477–1485 (1998).
[CrossRef]

F. M. Mims, “Solar corona caused by juniper pollen in Texas,” Appl. Opt. 37, 1486–1488 (1998).
[CrossRef]

1997

F. M. Ralph, P. J. Neiman, T. L. Keller, D. Levinson, L. S. Fedor, “Observations, simulations, and analysis of nonstationary trapped lee waves,” J. Atmos. Sci. 54, 1308–1333 (1997).
[CrossRef]

1995

A. J. Heymsfield, L. M. Miloshevich, “Relative humidity and temperature influences on cirrus formation and evolution: observations from wave clouds and FIRE II,” J. Atmos. Sci. 52, 4302–4326 (1995).
[CrossRef]

1994

1993

A. J. Heymsfield, L. M. Miloshevich, “Homogeneous nucleation and supercooled liquid water in orographic wave clouds,” J. Atmos. Sci. 50, 2335–2353 (1993).
[CrossRef]

1991

1989

C. M. R. Platt, J. D. Spinhirne, W. D. Hart, “Optical and microphysical properties of a cold cirrus cloud: evidence for regions of small ice particles,” J. Geophys. Res. 94, 11151–11164 (1989).
[CrossRef]

K. Sassen, D. O. Starr, T. Uttal, “Mesoscale and microscale structure of cirrus clouds: three case studies,” J. Atmos. Sci. 46, 371–386 (1989).
[CrossRef]

1984

A. J. Heymsfield, C. M. R. Platt, “Parameterization of the particle size spectrum of ice clouds in terms of the ambient temperature and ice water content,” J. Atmos. Sci. 41, 846–855 (1984).
[CrossRef]

1979

1953

J. Appleman, “The formation of exhaust condensation trails by jet aircraft,” Bull. Am. Meteorol. Soc. 34, 14–20 (1953).

1948

P. Queney, “The problem of airflow over mountains: a summary of theoretical studies,” Bull. Am. Meteorol. Soc. 29, 16–26 (1948).

1912

G. C. Simpson, “Coronae and iridescent clouds,” Q. J. R. Meteorol. Soc. 38, 291–299 (1912).
[CrossRef]

Appleman, J.

J. Appleman, “The formation of exhaust condensation trails by jet aircraft,” Bull. Am. Meteorol. Soc. 34, 14–20 (1953).

Bedard, A. J.

T. Q. Carney, A. J. Bedard, J. M. Brown, J. McGinley, T. Lindholm, M. J. Kraus, Hazardous Mountain Winds and Their Visual Indicators, NOAA Handbook (Environmental Research Laboratories, Boulder, Colo., 1996).

Bohren, C. F.

P. Parviainen, C. F. Bohren, V. Makela, “Vertical elliptial coronas caused by pollen,” Appl. Opt. 33, 4548–4554 (1994).
[CrossRef] [PubMed]

C. F. Bohren, D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, New York, 1983).

Brown, J. M.

T. Q. Carney, A. J. Bedard, J. M. Brown, J. McGinley, T. Lindholm, M. J. Kraus, Hazardous Mountain Winds and Their Visual Indicators, NOAA Handbook (Environmental Research Laboratories, Boulder, Colo., 1996).

Carney, T. Q.

T. Q. Carney, A. J. Bedard, J. M. Brown, J. McGinley, T. Lindholm, M. J. Kraus, Hazardous Mountain Winds and Their Visual Indicators, NOAA Handbook (Environmental Research Laboratories, Boulder, Colo., 1996).

DeMott, P. J.

H. Gerber, C. H. Twohy, B. Gandrud, A. J. Heymsfield, G. M. McFarquhar, P. J. DeMott, D. C. Rogers, “Measurements of wave-cloud microphysical properties with two new aircraft probes,” Geophys. Res. Lett. 25, 1117–1120 (1998).
[CrossRef]

Durran, D. R.

D. R. Durran, Mesoscale Meteorology and Forecasting, P.S. Ray, ed. (American Meteorological Society, Boston, 1986), pp. 472–492.

Fedor, L. S.

F. M. Ralph, P. J. Neiman, T. L. Keller, D. Levinson, L. S. Fedor, “Observations, simulations, and analysis of nonstationary trapped lee waves,” J. Atmos. Sci. 54, 1308–1333 (1997).
[CrossRef]

Gandrud, B.

H. Gerber, C. H. Twohy, B. Gandrud, A. J. Heymsfield, G. M. McFarquhar, P. J. DeMott, D. C. Rogers, “Measurements of wave-cloud microphysical properties with two new aircraft probes,” Geophys. Res. Lett. 25, 1117–1120 (1998).
[CrossRef]

Gedzelman, S. D.

Gerber, H.

H. Gerber, C. H. Twohy, B. Gandrud, A. J. Heymsfield, G. M. McFarquhar, P. J. DeMott, D. C. Rogers, “Measurements of wave-cloud microphysical properties with two new aircraft probes,” Geophys. Res. Lett. 25, 1117–1120 (1998).
[CrossRef]

Goodman, J. W.

J. W. Goodman, Introduction to Fourier Optics, 2nd ed. (McGraw-Hill, New York, 1996).

Hallett, J.

Hart, W. D.

C. M. R. Platt, J. D. Spinhirne, W. D. Hart, “Optical and microphysical properties of a cold cirrus cloud: evidence for regions of small ice particles,” J. Geophys. Res. 94, 11151–11164 (1989).
[CrossRef]

Heymsfield, A.

A. Heymsfield, Mesoscale and Microscale Meteorology Division, National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, Colo. 80301 (personal communication, 2001).

Heymsfield, A. J.

H. Gerber, C. H. Twohy, B. Gandrud, A. J. Heymsfield, G. M. McFarquhar, P. J. DeMott, D. C. Rogers, “Measurements of wave-cloud microphysical properties with two new aircraft probes,” Geophys. Res. Lett. 25, 1117–1120 (1998).
[CrossRef]

A. J. Heymsfield, L. M. Miloshevich, “Relative humidity and temperature influences on cirrus formation and evolution: observations from wave clouds and FIRE II,” J. Atmos. Sci. 52, 4302–4326 (1995).
[CrossRef]

A. J. Heymsfield, L. M. Miloshevich, “Homogeneous nucleation and supercooled liquid water in orographic wave clouds,” J. Atmos. Sci. 50, 2335–2353 (1993).
[CrossRef]

A. J. Heymsfield, C. M. R. Platt, “Parameterization of the particle size spectrum of ice clouds in terms of the ambient temperature and ice water content,” J. Atmos. Sci. 41, 846–855 (1984).
[CrossRef]

Huffman, D. R.

C. F. Bohren, D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, New York, 1983).

Keller, T. L.

F. M. Ralph, P. J. Neiman, T. L. Keller, D. Levinson, L. S. Fedor, “Observations, simulations, and analysis of nonstationary trapped lee waves,” J. Atmos. Sci. 54, 1308–1333 (1997).
[CrossRef]

Klett, J. D.

H. R. Pruppacher, J. D. Klett, Microphysics of Clouds and Precipitation (Reidel, Boston, 1980).

Kraus, M. J.

T. Q. Carney, A. J. Bedard, J. M. Brown, J. McGinley, T. Lindholm, M. J. Kraus, Hazardous Mountain Winds and Their Visual Indicators, NOAA Handbook (Environmental Research Laboratories, Boulder, Colo., 1996).

Levinson, D.

F. M. Ralph, P. J. Neiman, T. L. Keller, D. Levinson, L. S. Fedor, “Observations, simulations, and analysis of nonstationary trapped lee waves,” J. Atmos. Sci. 54, 1308–1333 (1997).
[CrossRef]

Lindholm, T.

T. Q. Carney, A. J. Bedard, J. M. Brown, J. McGinley, T. Lindholm, M. J. Kraus, Hazardous Mountain Winds and Their Visual Indicators, NOAA Handbook (Environmental Research Laboratories, Boulder, Colo., 1996).

Lock, J. A.

Mace, G. G.

Makela, V.

McFarquhar, G. M.

H. Gerber, C. H. Twohy, B. Gandrud, A. J. Heymsfield, G. M. McFarquhar, P. J. DeMott, D. C. Rogers, “Measurements of wave-cloud microphysical properties with two new aircraft probes,” Geophys. Res. Lett. 25, 1117–1120 (1998).
[CrossRef]

McGinley, J.

T. Q. Carney, A. J. Bedard, J. M. Brown, J. McGinley, T. Lindholm, M. J. Kraus, Hazardous Mountain Winds and Their Visual Indicators, NOAA Handbook (Environmental Research Laboratories, Boulder, Colo., 1996).

Mielke, B.

Miloshevich, L. M.

A. J. Heymsfield, L. M. Miloshevich, “Relative humidity and temperature influences on cirrus formation and evolution: observations from wave clouds and FIRE II,” J. Atmos. Sci. 52, 4302–4326 (1995).
[CrossRef]

A. J. Heymsfield, L. M. Miloshevich, “Homogeneous nucleation and supercooled liquid water in orographic wave clouds,” J. Atmos. Sci. 50, 2335–2353 (1993).
[CrossRef]

Mims, F. M.

Neiman, P. J.

F. M. Ralph, P. J. Neiman, T. L. Keller, D. Levinson, L. S. Fedor, “Observations, simulations, and analysis of nonstationary trapped lee waves,” J. Atmos. Sci. 54, 1308–1333 (1997).
[CrossRef]

P. J. Neiman, J. A. Shaw are preparing a manuscript to be called “Optical diffraction patterns in mountain wave clouds over northeastern Colorado.”

Parviainen, P.

Platt, C. M. R.

C. M. R. Platt, J. D. Spinhirne, W. D. Hart, “Optical and microphysical properties of a cold cirrus cloud: evidence for regions of small ice particles,” J. Geophys. Res. 94, 11151–11164 (1989).
[CrossRef]

A. J. Heymsfield, C. M. R. Platt, “Parameterization of the particle size spectrum of ice clouds in terms of the ambient temperature and ice water content,” J. Atmos. Sci. 41, 846–855 (1984).
[CrossRef]

Poellot, M. R.

Pruppacher, H. R.

H. R. Pruppacher, J. D. Klett, Microphysics of Clouds and Precipitation (Reidel, Boston, 1980).

Queney, P.

P. Queney, “The problem of airflow over mountains: a summary of theoretical studies,” Bull. Am. Meteorol. Soc. 29, 16–26 (1948).

Ralph, F. M.

F. M. Ralph, P. J. Neiman, T. L. Keller, D. Levinson, L. S. Fedor, “Observations, simulations, and analysis of nonstationary trapped lee waves,” J. Atmos. Sci. 54, 1308–1333 (1997).
[CrossRef]

Rogers, D. C.

H. Gerber, C. H. Twohy, B. Gandrud, A. J. Heymsfield, G. M. McFarquhar, P. J. DeMott, D. C. Rogers, “Measurements of wave-cloud microphysical properties with two new aircraft probes,” Geophys. Res. Lett. 25, 1117–1120 (1998).
[CrossRef]

Sassen, K.

Shaw, J. A.

J. A. Shaw, “The Christmas corona,” Opt. Photon. News (April1997), pp. 52–53.

P. J. Neiman, J. A. Shaw are preparing a manuscript to be called “Optical diffraction patterns in mountain wave clouds over northeastern Colorado.”

Simpson, G. C.

G. C. Simpson, “Coronae and iridescent clouds,” Q. J. R. Meteorol. Soc. 38, 291–299 (1912).
[CrossRef]

Smith, R. B.

R. B. Smith, “The influence of the mountains on the atmosphere,” in Advances in Geophysics, B. Saltzman, ed. (Academic, New York, 1979), vol. 21, pp. 87–230.
[CrossRef]

Spinhirne, J. D.

C. M. R. Platt, J. D. Spinhirne, W. D. Hart, “Optical and microphysical properties of a cold cirrus cloud: evidence for regions of small ice particles,” J. Geophys. Res. 94, 11151–11164 (1989).
[CrossRef]

Starr, D. O.

K. Sassen, D. O. Starr, T. Uttal, “Mesoscale and microscale structure of cirrus clouds: three case studies,” J. Atmos. Sci. 46, 371–386 (1989).
[CrossRef]

Trankle, E.

Twohy, C. H.

H. Gerber, C. H. Twohy, B. Gandrud, A. J. Heymsfield, G. M. McFarquhar, P. J. DeMott, D. C. Rogers, “Measurements of wave-cloud microphysical properties with two new aircraft probes,” Geophys. Res. Lett. 25, 1117–1120 (1998).
[CrossRef]

Uttal, T.

K. Sassen, D. O. Starr, T. Uttal, “Mesoscale and microscale structure of cirrus clouds: three case studies,” J. Atmos. Sci. 46, 371–386 (1989).
[CrossRef]

Whiteman, C. D.

C. D. Whiteman, Mountain Meteorology: Fundamentals and Applications (Oxford U. Press, New York, 2000).

Yang, L.

Appl. Opt.

Bull. Am. Meteorol. Soc.

P. Queney, “The problem of airflow over mountains: a summary of theoretical studies,” Bull. Am. Meteorol. Soc. 29, 16–26 (1948).

J. Appleman, “The formation of exhaust condensation trails by jet aircraft,” Bull. Am. Meteorol. Soc. 34, 14–20 (1953).

Geophys. Res. Lett.

H. Gerber, C. H. Twohy, B. Gandrud, A. J. Heymsfield, G. M. McFarquhar, P. J. DeMott, D. C. Rogers, “Measurements of wave-cloud microphysical properties with two new aircraft probes,” Geophys. Res. Lett. 25, 1117–1120 (1998).
[CrossRef]

J. Atmos. Sci.

F. M. Ralph, P. J. Neiman, T. L. Keller, D. Levinson, L. S. Fedor, “Observations, simulations, and analysis of nonstationary trapped lee waves,” J. Atmos. Sci. 54, 1308–1333 (1997).
[CrossRef]

A. J. Heymsfield, C. M. R. Platt, “Parameterization of the particle size spectrum of ice clouds in terms of the ambient temperature and ice water content,” J. Atmos. Sci. 41, 846–855 (1984).
[CrossRef]

A. J. Heymsfield, L. M. Miloshevich, “Homogeneous nucleation and supercooled liquid water in orographic wave clouds,” J. Atmos. Sci. 50, 2335–2353 (1993).
[CrossRef]

A. J. Heymsfield, L. M. Miloshevich, “Relative humidity and temperature influences on cirrus formation and evolution: observations from wave clouds and FIRE II,” J. Atmos. Sci. 52, 4302–4326 (1995).
[CrossRef]

K. Sassen, D. O. Starr, T. Uttal, “Mesoscale and microscale structure of cirrus clouds: three case studies,” J. Atmos. Sci. 46, 371–386 (1989).
[CrossRef]

J. Geophys. Res.

C. M. R. Platt, J. D. Spinhirne, W. D. Hart, “Optical and microphysical properties of a cold cirrus cloud: evidence for regions of small ice particles,” J. Geophys. Res. 94, 11151–11164 (1989).
[CrossRef]

J. Opt. Soc. Am.

Q. J. R. Meteorol. Soc.

G. C. Simpson, “Coronae and iridescent clouds,” Q. J. R. Meteorol. Soc. 38, 291–299 (1912).
[CrossRef]

Other

J. A. Shaw, “The Christmas corona,” Opt. Photon. News (April1997), pp. 52–53.

P. J. Neiman, J. A. Shaw are preparing a manuscript to be called “Optical diffraction patterns in mountain wave clouds over northeastern Colorado.”

C. D. Whiteman, Mountain Meteorology: Fundamentals and Applications (Oxford U. Press, New York, 2000).

H. R. Pruppacher, J. D. Klett, Microphysics of Clouds and Precipitation (Reidel, Boston, 1980).

R. B. Smith, “The influence of the mountains on the atmosphere,” in Advances in Geophysics, B. Saltzman, ed. (Academic, New York, 1979), vol. 21, pp. 87–230.
[CrossRef]

D. R. Durran, Mesoscale Meteorology and Forecasting, P.S. Ray, ed. (American Meteorological Society, Boston, 1986), pp. 472–492.

T. Q. Carney, A. J. Bedard, J. M. Brown, J. McGinley, T. Lindholm, M. J. Kraus, Hazardous Mountain Winds and Their Visual Indicators, NOAA Handbook (Environmental Research Laboratories, Boulder, Colo., 1996).

A. Heymsfield, Mesoscale and Microscale Meteorology Division, National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, Colo. 80301 (personal communication, 2001).

C. F. Bohren, D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, New York, 1983).

J. W. Goodman, Introduction to Fourier Optics, 2nd ed. (McGraw-Hill, New York, 1996).

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Figures (8)

Fig. 1
Fig. 1

Photograph of iridescent standing lenticular wave clouds above Boulder, Colorado, on 8 November 1995. This cropped photo was taken with a 70–210-mm focal length lens; the exact focal length is unknown.

Fig. 2
Fig. 2

In situ observations of frozen cloud particles in an upper-tropospheric mountain wave cloud at a pressure altitude and temperature of (a) 339.3 mb and -34.4 °C, and (b) 319.3 mb and -40.0°C. The classical ice crystals in (a), whose ∼100-μm size is shown for scale, are associated with a nearby nonorographic cirrus cloud, while the much smaller quasispherical particles in (b) are frozen wave-cloud particles (freezing of supercooled droplets on collection can be ruled out because drops larger than a few micrometers cannot exist colder than the homogeneous nucleation point of about -36 °C).17 These ice particles were collected in mountain wave clouds similar to the ones that produced the optical displays illustrated with photographs in this paper. Photos courtesy of Andy Heymsfield at the National Center for Atmospheric Research, Boulder, Colorado.17

Fig. 3
Fig. 3

Photograph of a circular corona above Nederland, Colorado, on 5 November 1989. The first-order red ring and the second-order blue and red rings are marked to the right of the Sun, and their radii are labeled in degrees. This cropped photo was taken with a 70-mm focal-length lens.

Fig. 4
Fig. 4

Photograph of an oblong corona above Boulder, Colorado, on 29 January 1987. The first-order red ring and the second-order blue and red rings are marked below and above the Sun, and their radii are labeled in degrees. This cropped photo was taken with a 70-mm focal-length lens.

Fig. 5
Fig. 5

Photograph of an asymptotic corona at the upwind edge of a wave cloud above Nederland, Colorado, on 31 May 1987. The first-order red ring is marked above and to the sides of the Sun, and the second- through fourth-order red rings are marked above the Sun; their angular radii are labeled in degrees. This cropped photo was taken with a 70-mm focal-length lens.

Fig. 6
Fig. 6

Photograph of a stepwise discontinuous corona above Boulder, Colorado, on 31 October 1989. The first-order red ring and the second-order blue and red rings are marked below and above the Sun, and their radii are labeled in degrees. This cropped photo was taken with a 70-mm focal-length lens.

Fig. 7
Fig. 7

Photograph of a ragged corona above Nederland, Colorado, on 15 January 1996. This cropped photo was taken with a 70–210-mm focal-length lens; the exact focal length is unknown.

Fig. 8
Fig. 8

Photographs of iridescence above Boulder, Colorado, on (a) 8 November 1995 and (b) 25 December 1998. These cropped photos were taken with 70–210- and 28–200-mm focal-length lenses, respectively. The exact focal length in (a) is unknown, and the focal length in (b) is ∼120 mm.

Tables (1)

Tables Icon

Table 1 Mean Wind, Moisture, and Temperature Characteristics from the Relevant Denver and Grand Junction Rawinsonde Soundings for the Diffraction Displays Shown in Our Photographsa

Equations (3)

Equations on this page are rendered with MathJax. Learn more.

Ir=πd24λz22J1πdrλzπdrλz2
πdrλz=πd tanθλπd sinθλπdθλ.
sinθ=mλ/d,

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