Cold spots have long been associated with paranormal phenomena. Probably one of the most common pieces of equipment found in most investigators toolbox is a thermometer. Some thermometers used by investigators today are of the the non-contact infrared type which  only measure surface temperatures and not ambient air temp. But since someone saw someone improperly using it on a TV show trying to find cold spots, the trend was started.

Infrared thermometers work by capturing the invisible infrared energy naturally emitted from all objects that are above absolute zero, microwaves, visible light, ultraviolet, gamma and x-rays. Every object emits infrared energy as long as it's warmer than absolute zero. Ambient temperature is area or air temperature not object temperature.

Infrared thermometers need a surface to measure a temperature. All infrared thermometers are specifically designed so that air between the sensor and the target does not affect the surface temperature measurement. Therefore, using and IR thermometer to read temperature changes in the air or try to find a cold spots is useless.

Thermal imaging cameras or (FlLIR), which stands for Forward Looking Infrared  have become a popular tool with some paranormal groups looking for cold spots and ghosts.

These cameras work exactly like a non-contact infrared thermometer. Except instead of having one point they have a collection of many points all combined together forming a video picture. Just like the IR non-contact thermometer the thermal camera will only measure temperature of surfaces, but not ambient air temperatures. They will not measure the temperature of fog, smoke, or mist. The inability to measure the temperature of smoke is the main reason thermal cameras are used by fire departments to locate victims in burning buildings, they allow the firemen to see through the smoke to the surface of a solid object.  Most of the evidence that has been presented on the TV shows from thermal cameras have been the result of improper use and interpretation of reflections as anomalies or the result of an actual reflection of a solid surface. So save your money and just buy a good fast updating thermometer with a ambient temperature probe and you will be measuring the temperature of the air instead of the wall.

The video below is a good explanation by thermal camera experts on a what the capabilities of the thermal camera are and are not. The camera will not read the temperature of smoke, mist, or fog, and cannot find cold spots in the air.

 
Original Video - More videos at TinyPic

Original Video - More videos at TinyPic