They are quite common in most forms of art seems to be the best answer for your question :)
Action, just a guess hope it helps
Answer:
Sfumato was pioneered by Da Vinci. Sfumato is an Italian term meaning "smoky". It is a painting technique that creates the effect of a soft haze, or a sense of atmosphere. Sfumato was used by various Renaissance artists, including Leonardo da Vinci.
Hope this helps!
