Can IR thermometer measure air temperature?
Yes and no. No, because air (i.e., Oxygen and Nitrogen molecules) do not emit infrared radiation. However, you can aim an IR thermometer at anything having the SAME temperature as the air such as a leaf or grass (under sunshade) or indoors such as your desk, a piece of paper having the same temperature as the air. The key to measuring “air temperature” is to measure “anything that should have the same temperature as the air”.
