Photo of Dead Tree with Infrared EffectHere's the same photo again but after creating an infrared camera effect. Infrared cameras create their images using infrared light. Light waves in the infrared range are far longer than in the visible light spectrum. Infrared light is emitted from a body based on its heat characteristics and infrared cameras are designed to detect this range of radiation. Infrared cameras don't need visible light since infrared radiation is emitted by all bodies night and day. So a photo taken with an infrared camera can be taken even at night. Perhaps you are familiar with "night-vision goggles" used by the military - these work on the same principle of detecting the heat emit ed by a body in the infrared spectrum and forming an image from this "light".
This photo wasn't actually taken with an infrared camera; I used Photoshop to simulate what the image might look like had it been taken with an infrared camera. Photos taken with an infrared camera are often monochromatic since the sensor in the camera is typically designed to respond to a single wavelength within the infrared spectrum. For this reason they produce pictures that are very white and fuzzy at the points where the most heat is being generated. I like to try and simulate this effect to give a twist to the typical black and white image.
You can read more about infrared cameras at the following WikiPedia listing: http://en.wikipedia.org/wiki/Infrared_camera