A rainy evening is a demonstration from "Light and Texture" by James Toogood. It is done with multi layers of both optical and physical color mixes.
Some of the techniques include dropping colors into dry paper and allowing the paint to dry before dropping other colors on top of some lower layers.
This method was used to get the multi faceted look of the wet sidewalk. The city perspective (umbrella, raincoat,) the haze of the drizzle, and the light which bounces off the buildings all add to the effect and the feel of this painting.