In logic way I know what you are saying, but I can’t repeat it with my poor skills 
I created parameter as a vector (it doesn’t matter for me which type) to separate XYZ to RGB.
Then I opened level blueprint, there I made for my directional light rotation on tick only on Y axis multiplied by time and I updated my light rotation and sky. Now I don’t know how to get that angle im using to set the parameter - I dont know how to take it and set it and then I dont know how to put it into material(probably because I didnt made set part right) - I only know that for angle on Y from 0-180 is perm 0, and from 180-250-360 is gradient 0-1-0