Which factor is NOT listed as a measurement adjustment in infrared temperature readings?

• A. Emissivity changes
• B. Reflected apparent temperature
• C. Ambient temperature
• D. Wavelength selection

Answer: (D)

In infrared temperature readings, you correct the measurement by accounting for how a surface emits energy (emissivity), the energy reflected from the surroundings (reflected apparent temperature), and the ambient temperature around the measurement (ambient temperature). Emissivity changes are needed because real surfaces aren’t perfect emitters, so you adjust the reading to reflect that. Reflected apparent temperature matters because the sensor picks up not just the target’s energy but also energy reflected from nearby objects. Ambient temperature influences the background radiation and the energy reaching the sensor. Wavelength selection, however, is a characteristic of the instrument’s spectral band and how its detector responds, not a correction you apply to the measurement itself. Therefore, wavelength selection is not listed as a measurement adjustment.