December 21, 2018
Thermal Cameras are used to produce a graph represented heat signature emitted by the object it is focused on.This way, beekeepers can have an internal view of the beehive, how the heat is distributed within and the relative intensity of that heat. Although thermal images will display a temperature reading at the reticle, this reading is on the external surface of the object. This is not the internal temperature of the beehive. To acquire an internal temperature a thermal conductive probe would need to be inserted through an opening into the cluster. The displayed temperature reading in the thermal image will be close to the ambient air temperature, or a little higher if there is strong sunlight, and/or heat transmitted from inside.
With the thermal camera insights the camera provides, beekeepers can segregate colonies infected with diseases such as American or European foulbrood, and dispose of contaminated equipment used in containers. That will prevent bees that survived the winter from pillaging contaminated honey from the collapsed hives, and thereby spreading the disease to healthy colonies in the spring. Although varroa mites are another cause of colony collapse, there is a lesser risk of the infestation spreading to neighboring hives in the spring because the parasites usually die with their hosts in the winter.
A winter cluster of bees produces heat. And even though the bees in the outer shell of the cluster act as insulation keep the heat within the cluster, they are imperfect as insulators and some of that heat escapes. The variation in temperature difference could reasonably be related to the size of the cluster generating heat, with a larger cluster generating more heat and therefore showing a greater temperature difference between the empty super and the temperature through the inner cover. Using the infrared thermometer provides a relatively noninvasive means of verifying the viability of the colonies, and if my speculation about the significance of the variation in the magnitude of the temperature difference proves to be correct, it may also provide information about the size and/or location of the cluster within the hive.
Thermal Cameras are primarily be used to confirm viability of the colonies, but it can also keep records of the temperature differences and visual observations to see if any identifiable patterns of temperature, colony viability, and winter cluster location emerge. This provides an excuse to stay actively involved with the bees even in the coldest months of the year. Thermal cameras revealed how individual heater bees warm up the nest to precisely the right temperature.