I have a NIST-traceable Fluke 289 multimeter and thermocouple. The other day, I was measuring some unrelated temperatures and decided to check out the temperature environment near my AIR. Relative to the thermocouple, the AIR was reading 5-6 degrees high. The thermocouple tip was placed within inches of the AIR, and the entire thermocoupld/multimeter ensemble was in the same shaded environment.
Understandably, some may think the calibration on the thermocouple is off, but it agrees closely with other known temperature sources and thermometers.
Anyone have any thoughts as to why such a big difference?