Ever been to Texas when summer storms are coming and going? Not a lot done to this one...it's pretty natural. Be careful when stating an opinion, not to state it as fact...unless you are an expert...and happen to know something, as a fact.
What I mean is - sky is not natural because of dark navy above and high contrast of the clouds. I'm not saying that this is fake - i mean, that it looks diffrent when observer watching at it his eyes, not your camera.