What is the purpose of this scene? What additional natural, or "unnatural," events further the "crime against nature" theme?

THis is meant as a little comic relief at the height of tension. Duncan is dead and the old porter plays for some laughs. Of course he follows the theme of equivocation once again. The others talk about the "unnatural events". When a King is killed, the Elizabethan universe is turned sideways. God's order has been disturbed and "unnatural events" take place with the weather and animals.

Hey Kayla, make your questions shorter or they won't show up on the system.