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Fig. 5a: Thermal image of a 4x4 km? area in the Rhine Valley 8 km 
northwest of Freiburg i.Br. 
The terrain is partly wooded, the villages Gottenheim and 
Umkirch are in the upper left and lower right corners re- 
spectively (2. April 1976, 5.25 h, altitude 2000 m) 
Fig. 5b: Same image as 5a, equidensity representation, 19 C - grey 
tones ranging from < 0° (dark) to > 5° (light)