Infrared thermography provides one with a
picture of the momentary temperature distribution on the earth’s
surface at high powers of resolution, impossible to obtain with
any stationary measurement network. From an airplane, the
landscape is scanned line by line with the measuring photometer
(with a ground resolution of about 7 m by 7 m at an altitude of
3,000 m).
The vivid expressions that infrared
thermography produces are not unproblematic in every respect,
since individual IR-heat images do not communicate definite
findings on the multilayered problem of climate. The measured
surface temperatures are above all not identical with the local
air temperatures.
Nevertheless, infrared thermography provides
indications of variations in temperature structures (e.g. heat
islands, cold-air collection areas, cold-air drainage areas)
caused by human settlement in an urban area. The execution of at
least two flyovers (evening and morning) makes possible the
generation of information about the cooling behavior of
individual areas (Figure 5/1a -
5/1d). In addition, indications can be
obtained regarding climatically preferential areas and local
climate facts such as local air exchange processes, cold air
blockage, and conflicts with existing uses. Strategies can also
be developed for more in-depth measurements on the ground.
Such conclusions require, however, a realistic
conception of the interaction of meteorological parameters in
the air layer near the ground, knowledge of the local land
conditions, and additional meteorological information.
The specified temperature color scale in an
infrared picture corresponds to psychologically-perceived
criteria (red = warm, blue = cold). Darker surfaces are open
areas with low vegetation; strongly-cooling surfaces are
depicted in black. Noticeable as warm examples are both waters
and inner-city areas with their respective street structures.
