How to use the JS Incidence shader

Download example scene here.
To keep the size of the example scene down I have replaced the file textures
with noise textures and reduced the number of polygons on the terrain.

The JS_Incidence node calculates the incidence angle between the objects normals
and one of the available axis and outputs a scalar value between 0 and 1. (You could think of it as 0 to 100%.)
It could be useful for positioning textures like snow on terrain
with one texture on sloped and another on flat surfaces.

This can be used to drive other shaders like the JS_BlendColors blend value or a Ramps coordinate
to decide where a certain color should be visible.

The JS_Incidence is connected to a JS_BlendColors Blender and then to color of a Lambert shader.
In this example two filetextures were connected to the JS_BlendColors color inputs.

Use the Parameters for Bias and Gain to control the position and falloff.
You could even try connecting a small noise texture to the Bias to add a little randomness to the position.

The haze was simply made with a mib volume shader connected to the camera as a MR volume shader.

Good luck!