Reference picture 
Study in oils
Big clouds in the sunset in video
Big cloud in the sunset in watercolor - ENGLISH VERSION
Supplies :
Brush : Escoda Último 1″.
Paper : Canson Héritage rough.
Colors : Indanthrene blue (Sennelier), Cobalt blue (Schmincke), Winsor red (Winsor & Newton), Nickel azo yellow (Daniel Smith), Burnt sienna (Daniel Smith).
And here you have the finished painting (Click to enlarge) :
