Mr. Turner Timothy Spall, Dorothy Atkinson, Marion Bailey. Directed by Mike Leigh. Rated R. Opens Friday.

“Humans!” harrumphs painter J.M.W. Turner (Timothy Spall) in Mike Leigh’s sprawling, unconventional biopic Mr. Turner, a portrait of the artist as an old crank. Providing virtually no context for his story of the renowned landscape artist’s later years, Leigh strings together scenes that are alternately funny, sad, bitter and baffling, sometimes all at the same time. A curmudgeonly misanthrope who grunts and grumbles as often as he speaks actual sentences, Turner devotes so much energy to his chaotic paintings of ships and trains that he has very little patience for human interaction. Yet Spall gives the man depth and feeling at unexpected moments, even when his reactions appear inexplicable.

It’s sometimes frustrating to watch scenes of Turner interacting with fellow artists and intellectuals and not have a clear idea of who they are, but Leigh gives a rich sense of Turner as a human being, from his fraught interactions with his family to his dysfunctional romantic relationships (he treats his long-suffering housekeeper like a combination of a Roomba and a RealDoll). The Oscar-nominated cinematography by Dick Pope is gorgeous, frequently evoking Turner’s own work. Turner himself is not nearly as majestic, but that’s what makes him a perfect subject for Leigh’s typically earthy storytelling.