Identification of warm and cool zones at the surface of a giant honeybee nest.

(A-C) IR overlays upon synchronously recorded HD images at different HD/IR transparency levels: panel A, 100/0; B, 50/50; C, 0/10 in per cent. Left side, overview of nest 02, white open inset rectangles regard to the close-up images on the right side, in which the small green spots mark the isotherm level (27.6° - 27.7°C); rainbow-900 scales (21° - 34°C) on the right side of the image panels. White horizontal lines in the right image panels (A, C) are detection lines with the length of 38 cm. (D) Black curve, temperature values [°C] scanned along the detection line in the IR image (panel C); the vertical orange bars give the positions of the bee bodies along this line as assessed by image analysis (panel A).