Noncontact thermal devices measure which atmospheric property?

• A. Gas concentration
• B. Humidity
• C. Pressure
• D. Temperature

Answer: (D)

Noncontact thermal devices measure temperature by detecting infrared radiation emitted by objects and converting that energy into a temperature reading. The infrared energy a surface emits is tied to its temperature (with adjustments for emissivity), so these tools give you the temperature of what they’re pointed at without touching it. Gas concentration, humidity, and pressure aren’t read directly by this method—they require different sensing principles (spectroscopy for gases, dedicated humidity sensors, and pressure transducers). So the property being measured is temperature.