On the evening of 25 November 1998, a cirrus cloud revealing the pastel colors of the iridescence phenomenon was photographed and studied by a polarization lidar system at the University of Utah Facility for Atmospheric Remote Sensing (FARS). The diffraction of sunlight falling on relatively minute cloud particles, which display spatial gradients in size, is the cause of iridescence. According to the 14-year study of midlatitude cirrus clouds at FARS, cirrus rarely produce even poor iridescent patches, making this particularly long-lived and vivid occurrence unique. In this unusually high (13.2–14.4-km) and cold (−69.7 ° to −75.5°) tropopause-topped cirrus cloud, iridescence was noted from ~6.0° to ~13.5° from the Sun. On the basis of simple diffraction theory, this indicates the presence of particles of 2.5–5.5-μm effective diameter. The linear depolarization ratios of δ = 0.5 measured by the lidar verify that the cloud particles were nonspherical ice crystals. The demonstration that ice clouds can generate iridescence has led to the conclusion that iridescence is rarely seen in midlatitude cirrus clouds because populations of such small particles do not exist for long in the presence of the relatively high water-vapor supersaturations needed for ice-particle nucleation.

© 2003 Optical Society of America

[Optical Society of America ]

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Log in to access OSA Member Subscription

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Log in to access OSA Member Subscription

You do not have subscription access to this journal. Article level metrics are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Log in to access OSA Member Subscription

Related Journal Articles

• Lidar Inelastic Multiple-Scattering Parameters of Cirrus Particle Ensembles Determined with Geometrical-Optics Crystal Phase Functions (AO)
• Scattering Properties of Needlelike and Platelike Ice Spheroids with Moderate Size Parameters (AO)
• Midlatitude Cirrus Cloud Climatology from the Facility for Atmospheric Remote Sensing. IV. Optical Displays (AO)
• Light Tunneling in Clouds (AO)
• Icy wave-cloud lunar corona and cirrus iridescence (AO)

Related Conference Papers

• Laser sounder approach for measuring atmospheric CO2 from orbit
• Raman-shifted eye-safe aerosol lidar development
• Differential Absorption Lidar Using NH3-CO2 Laser
• Airborne Lidar and Satellite Comparison of Atmospheric Aerosols
• The CSU Sodium Lidar Facility: Current Observation Capability and Science