A pleasant surprise this morning, at home, just after waking up and opening the window. Too bad I was still too sleepy and used too short a shutter time, so the camera went to ISO 1600...
Nikon D200 + Nikkor 12-24mm ƒ/4G DX AF-S @ 12 mm, 1/250 sec @ ƒ/4, ISO 1600
Rainbow.