Thermal Imaging of people and background temperature

[Anand Sivaram]

Any object with a temperature emits corresponding EM waves.
Thermal imaging works by considering our temperature of 37C/98.4F/310K, and it corresponds to 9.3um LWIR as per Wien's law.

I was thinking about the following summer scenarios in which how it would work.

1) If the atmospheric temperature is at the same 37C, human beings and all surroundings are at the same temperature. Would we be able to see a person using thermal imaging?

2) Even higher air temperature, let us say at 40C/104F, human beings might have lower temperature than the surroundings because of sweating. Would we be able to see a person still?

 

[sophiecentaur]

A thermal imager looks at the em radiation from a source. The air in between will have some input but the image would be dominated by the target and the actual background. After a day of serious cooking by the Sun, some of the background surfaces would be 'warm to the touch' (cooling rapidly by radiation into space) but there could be low contrast in an image of a body in front of those surfaces.
The shape of a target would also help to recognise it against a background, even if the background is relatively warm.