Zmierzch cywilny and other 80,800 icons from Icons8 icon pack follow the visual guidelines of the operating systems: Windows, iOS, Android KitKat, and Material. PNG format is free up to 100x100 px. Icons are availble for download in PNG and vector (SVG, PDF, EPS, and more).
This is a picture of the sun coming out of a horizontal line. underneath the line is the rest of the sun, but it's made of dotted lines instead of solid. in the center of the sun it says "6 degrees" with the degree sybol