The pond.

Infrared Photography Lecture #2
What humans see as visible light is only a small section of the electromagnetic spectrum (between 400 and 700 nm) and even that can be broken down into the rainbow of violet at the low end (even lower would be ultraviolet light) moving into blue, green, yellow orange and red, then just beyond is infrared. X-rays and radio waves are also part of the electromagnetic spectrum, but fortunately we don’t see all that mess. This infrared photography picks up “near” infrared, while surveillance cameras and spy cameras that can detect warm bodies are using “far” infrared.