Infrared photography
Infrared (IR) photography opens the window to a world usually not visible to our naked eyes. To see and explore it, one has to 'unlock' a digital camera, i.e. remove the filter in front of the sensor, which blocks the IR light and replace it by one which blocks most of the visible light. I had a digital camera modified by http://www.irrecams.de/.
IR radiation has longer wavelengths than visible light. The part of the IR light used in IR photography as shown here are the wavelengths just adjacent to the visible light, therefore called near IR (not to be confused with thermal imaging, at much longer wavelenths, the far IR). Light transmission and reflections of matter are already different in this wavelength range. For example, botany mostly appears bright white due to the Wood effect. Absorption and transmission of liquids such as water can be completely different (e.g. making water appear often very dark), and the ratio of Rayleigh scattering (~ƒ^4) and Mie
scattering (~ƒ^2) is altered in this different frequency range, resulting in a different contrast of clouds and blue sky (admittedly the sky in IR images would not be blue, since the concept of colors is strictly limited to the range of visible light - but there are ways to make it appear blue on IR photos...). If you are interested in learning more about the physics of IR photography, I can recommend reading on http://eye.de/irstart.shtml, where you can even find the link to an interesting scientific article in Eur. J. Phys.
The result of this technique are images that appear mystical, sometimes even a bit spooky, but in any case interesting and exceptional. Take a look here at some examples to make up your own mind...
A few more IR images can be found on the site about Norway.
