ASD Document 600540 Rev. J 60 FieldSpec® 3 User Manual
www.asdi.com Chapter 7 Field Measurements
7.5 Clouds
The presence of partial cloud cover is indicative of highly spatially and
temporally variable atmospheric water vapor.
Because of the large influence of water vapor on the atmospheric transmission
(see
Figure 7-2), variability of atmospheric water vapor between the time
when the reference and target measurements are made will result in errors in
the resultant spectrum.
Note: This error can be reduced by minimizing the length of time between the
measurement of the reference sample and the target.
While they are difficult to see and often appear inconsequential, the presence
of cirrus clouds tends to educe significant variability in atmospheric water
vapor.
Figure 7-4 Transmission spectrum of various gases for a typical
atmospheric conditions.
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