It's almost spring down here in NZ, but we still have quite cool mornings, resulting in come thick early-morning fogs. When I looked out at the fog-filled valley below me, I knew I had to get up high without major obstructions to get a clear shot. So, I whizzed up to the top of Auckland's Wiakumete Cemetery to be greeted by this.
While this is caused by cold layers and moisture, it reminds me of images sent by friends in British Columbia of similar effects caused by heat, smoke and fire..
Thanks for your comments John. I am a fan of greyscale photography when colour is not going to contribute to the image, and in fact may be a distraction. Given we are automatically attracted to colours (warm, bright and saturated being the most impactful), I like to go to greyscale when I want to concentrate on tone, texture and form: what was more the case here.
I am personally a bit pedantic about nomenclature here... I go with the definition that monochrome is an image containing only one colour, as in these examples (noting that white and black are not colours per se): obviously, in these two examples the colour is blue. The first concentrates on pattern and texture, while the second is all about tonal values.
To me, Greyscale is for those images that have no colours, but a tonal range from white, through greys to black. Often used for artistic effect and portraits. As Ted Grant said "When you photograph people in colour, you photograph their clothes. But when you photograph people in Black and white, you photograph their souls!” 
Alternatively, I might use greyscale for texture or patterns:
I reserve the term Black and White for those images that contain elements that are purely black or purely white, but without the tonal values of grey in between. These images are much more difficult to capture, but conform to a Japanese artistic concept called Notan - Light / Dark Harmony, which emphasizes structured lights and darks, an organic design and/or an interesting pattern. The following image was taken of a strongly backlit bus shelter, for example.
