Cirrus Clouds
Name
amsmonographs-d-16-0010.1.pdf
Size
2.01 MB
Format
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Checksum (MD5)
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Author(s)
Heymsfield, Andrew J.
Krämer, Martina
Luebke, Anna
Brown, Phil
Franklin, Charmaine
Lawson, Paul
Lohmann, Ulrike
McFarquhar, Greg
Ulanowski, Zbigniew
Van Tricht, Kristof
Date Issued
January 2017
Journal
Meteorological Monographs
Publisher
American Meteorological Society
Citation
Heymsfield, Andrew J. et al. “Cirrus Clouds.” Meteorological Monographs 58 (January 2017): 2.1–2.26 © 2017 American Meteorological Society
Version
Final published version
Abstract
The goal of this chapter is to synthesize information about what is now known about one of the three main types of clouds, cirrus, and to identify areas where more knowledge is needed. Cirrus clouds, composed of ice particles, form in the upper troposphere, where temperatures are generally below −30°C. Satellite observations show that the maximum-occurrence frequency of cirrus is near the tropics, with a large latitudinal movement seasonally. In situ measurements obtained over a wide range of cirrus types, formation mechanisms, temperatures, and geographical locations indicate that the ice water content and particle size generally decrease with decreasing temperature, whereas the ice particle concentration is nearly constant or increases slightly with decreasing temperature. High ice concentrations, sometimes observed in strong updrafts, result from homogeneous nucleation. The satellite-based and in situ measurements indicate that cirrus ice crystals typically differ from the simple, idealized geometry for smooth hexagonal shapes, indicating complexity and/or surface roughness. Their shapes significantly impact cirrus radiative properties and feedbacks to climate. Cirrus clouds, one of the most uncertain components of general circulation models (GCM), pose one of the greatest challenges in predicting the rate and geographical pattern of climate change. Improved measurements of the properties and size distributions and surface structure of small ice crystals (about 20 μm) and identifying the dominant ice nucleation process (heterogeneous versus homogeneous ice nucleation) under different cloud dynamical forcings will lead to a better representation of their properties in GCM and in modeling their current and future effects on climate.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1175/AMSMONOGRAPHS-D-16-0010.1
