EDL is a real time shading filter that enhances very small features on blank clouds or meshes (i.e. it doesn't rely on any information apart from the geometry itself). As the SSAO shader, this is a faster alternative to normal-based shading.
For more information about how EDL works, refer to this article: http://www.kitware.com
Note: EDL requires a contiguous depth map. Therefore if your cloud is too sparse at the current viewing zoom, you must increase the point size (so as to fill the holes).