Wikipedia:Wikiday

Wikiday is an idea to break up the 24-hour day into three color zones to make for easier real-time meeting and coordination. The graph is intended to make understanding time zone shifts easier, by using color to represent the local time of day: from light-blue morning to orange dusk to dark-blue late night. Vertically, the zones are placed in same-time relation to each other. (See main article on Wikiday)

The three main timezones used are China (CST), United Kingdom (GMT), and the west coast of North America (PST). The color zones are blue, green, and orange, representing the synergy times between main local areas; for example the Blue zone is where Asia and Europe share daylight. Where the zones change represents common meeting times for all zones, although one must rise early and another must stay up late to coordinate a meeting. Considering that members of a group may be skewed to one region or another, more convenient meeting times can quickly be calculated.

A day progresses from left to right. If GMT 12 noon is the base, PST local time is early morning, and China time is 8 pm, etc.