Nature!
Throughout the novel, a careful reader should notice that nature often mimics the characters' moods. The inteaction of the weather and other natural forces provides a constant accompaniment to the events of the novel.
In Chapter Ten the nature mimics the moods so well that it feels like its own separate character. When Varenukha leaves the theatre, the wind blows sand into his eyes "as though to warn him or to bar his way." When Behemoth punches Varenukha, the sky "echoed with a clap of thunder," and again when Azazello punches him, "there was an answering crash in the sky."
In Chapter Eleven the nature continues to mimic Ivan's moods. When he becomes upset over not being able to accurately describe Berlioz's death "water tumbled down in a solid sheet." As Ivan continues to cry and break down, the storm strengthens and "blankets the woods." But when Ivan is injected and calms down, so does the weather.
In Chapter Thirty the weather continues to mirror the character's emotions. The storm that formed when Matthew Levi asked to grant the Master and Margarita peace was beginning to clear. As they mount the horses, the storm cloud "rushed to meet the riders" and as the fly over the city, "the first drops were falling."
The weather is explained a bit in the epilogue. "But it is not the executioner who is frightening so much as the unnatural lighning in this dream, caused by some dark cloud boiling and heaving itself upon the earth, as happens only during world catastrophes." Here Ivan realizes that the scene of Yeshua's execution is only scary because of the horrific weather.
