traditional would be a stove with a wooden base and a brick exterior with a open valve leading to the end of the bright chimney. A modern one can have partially exposed smoke / steam valve to release pressure, while also having iron/ glass plates on top to allow for higher melting capabilities, with the addition of dials for more control when heating food.
Answer:
It foreshadows the ominous actions which will occur later within the play. It also distinguishes the witches as evil forces.
The weather may be a fallacy, it mirrors the moods of the characters during a given scene. The intensity of the thunder and lightning mirrors the intensity of emotion later within the act.
