Infrared thermometers, also known as non-contact thermometers or temperature guns, do not directly measure the ambient temperature of the air. Instead, they measure the infrared radiation emitted by objects within their field of view. This means that when you point an infrared thermometer at the air, it is likely measuring the radiation emitted by the closest objects rather than the actual air temperature.
The measurement of infrared radiation allows these thermometers to estimate the temperature of objects based on the amount of radiation they emit. Different materials and surfaces emit and reflect infrared radiation differently, which is why the thermometer readings can vary depending on the target object.
When you aim an infrared thermometer at the air, it will primarily detect the infrared radiation coming from objects that are in its line of sight. This can include nearby walls, furniture, or other surfaces. The thermometer will provide a reading based on the radiation received from those objects rather than the true ambient air temperature.
To measure the ambient air temperature accurately, it is generally more reliable to use a traditional thermometer, such as a mercury or digital thermometer, which directly senses the air temperature.