Talking about the weather...

The weather project by Olafur Eliasson was installed at the London's Tate Modern in 2003 as part of the popular Unilever series. The installation filled the open space of the gallery's Turbine Hall.

This hugely popular exhibit explored that most British of obsessions, the weather. What looks like a complete Sun is actually only half a circle, reflected by a mirror running the entire length of the high ceiling.
The light Eliasson's created is really interesting: with monochromatic yellow light eliminating all colour and spurts of 'mist' adding to the atmosphere, the building was transformed into an ethereal and disconcerting beauty.
Generally used in street lighting, mono-frequency lamps emit light at such a narrow frequency that colours other than yellow and black are invisible, thus transforming the visual field around the sun into a vast duotone landscape. (From Tate Modern: About the installation)