Chapter 9
Properties of Clouds and Cloud
Systems
William B. Rossow
NASA Goddard Institute for Space Studies
New York, NY 10025
USA
9.1 Introduction
Observations of clouds from the surface, aircraft and spacecraft give the impression of great
complexity and variability. Quantitative descriptions of the variety of clouds and determination
of its causes have been limited by lack of comprehensive and systematic observations that cover
the full range of space and time scales over which clouds vary. Now, there are two cloud
datasets that cover scales from 30 km and 3 hr up to the whole globe for more than a decade,
giving us, for the first time, a truly global view of clouds and their variability. One dataset
provides information on cloud cover, cloud base heights and cloud morphology from several
decades of surface weather observations (Warren et al., 1986, 1988; Hahn et al., 1995). These
observations can be supplemented by balloon measurements of the profiles of atmospheric
temperature and humidity that can provide information about cloud layer structure (Poore et
al., 1995; Wang and Rossow, 1995). Much more detailed cloud observations of global cloudiness
are possible using satellite remote sensing. A comprehensive survey of cloud cover, cloud
top temperature/pressure and visible optical thickness has been produced from more than a
decade of observations from the international constellation of weather satellites (Schiffer and
Rossow, 1983; Rossow and Schiffer, 1991). Newer satellite instruments and analysis techniques
extend the list of cloud properties that can be measured by satellites. Combining all of these
results provides the best available survey of cloud properties and also indicates what satellite
instruments should be included in a future cloud observing system.
9.2 Remote Sensing of Clouds
Satellites measure radiation, so a physical model of the interaction of radiation in cloudy atmospheres is needed to retrieve cloud properties from the satellite measurements (e.g. Goody
NATO ASI Series. Vol. 145
Radiation and Water in the CHmate System:
Remote Measurements
Edited by Ehrhard Raschke
© Springer-Verlag Berlin Heidelberg 1996
Properties of Clouds and Cloud
Systems
William B. Rossow
NASA Goddard Institute for Space Studies
New York, NY 10025
USA
9.1 Introduction
Observations of clouds from the surface, aircraft and spacecraft give the impression of great
complexity and variability. Quantitative descriptions of the variety of clouds and determination
of its causes have been limited by lack of comprehensive and systematic observations that cover
the full range of space and time scales over which clouds vary. Now, there are two cloud
datasets that cover scales from 30 km and 3 hr up to the whole globe for more than a decade,
giving us, for the first time, a truly global view of clouds and their variability. One dataset
provides information on cloud cover, cloud base heights and cloud morphology from several
decades of surface weather observations (Warren et al., 1986, 1988; Hahn et al., 1995). These
observations can be supplemented by balloon measurements of the profiles of atmospheric
temperature and humidity that can provide information about cloud layer structure (Poore et
al., 1995; Wang and Rossow, 1995). Much more detailed cloud observations of global cloudiness
are possible using satellite remote sensing. A comprehensive survey of cloud cover, cloud
top temperature/pressure and visible optical thickness has been produced from more than a
decade of observations from the international constellation of weather satellites (Schiffer and
Rossow, 1983; Rossow and Schiffer, 1991). Newer satellite instruments and analysis techniques
extend the list of cloud properties that can be measured by satellites. Combining all of these
results provides the best available survey of cloud properties and also indicates what satellite
instruments should be included in a future cloud observing system.
9.2 Remote Sensing of Clouds
Satellites measure radiation, so a physical model of the interaction of radiation in cloudy atmospheres is needed to retrieve cloud properties from the satellite measurements (e.g. Goody
NATO ASI Series. Vol. 145
Radiation and Water in the CHmate System:
Remote Measurements
Edited by Ehrhard Raschke
© Springer-Verlag Berlin Heidelberg 1996