Water Vapour (6.8 µm)
Moisture
or water vapour is present in the troposphere at different levels. This
Water vapour absorbs and re-radiates electromagnetic radiation in the
absorption band 6 -7 µm. This property is used for detecting presence of
moisture in the middle and upper levels (600 -300 hPa) of the
atmosphere. Dark region or black portion in WV imagery indicates an area
of high temperature and the dryness of upper and middle atmosphere and
bright region or white portion in WV imagery depicts an area of low
temperature and moist upper and middle atmosphere or presence of
tall/high cloud. WV image also provides information about the swirling
middle tropospheric wind patterns and jet streams.
Summary
Sensitive to moistureShows variations in upper tropospheric moistureTypically senses upper half of troposphere; higher in moist and lower in dry regionsAtmospheric wave structures are very apparent; short waves readily seenTracking features in sequences of water vapour images useful for inferring atmospheric motion (particularly moisture)
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