How does Golding use imagery to create a foreboding atmosphere? Provide the specific details from chapter 9.

From the text:

Over the island the build-up of clouds continued. A steady current of heated air rose all day from the mountain and was thrust to ten thousand feet; revolving masses of gas piled up the static until the air was ready to explode.

Colors drained from water and trees and pink surfaces of rock, and the white and brown clouds brooded. Nothing prospered but the flies who blackened their lord and made the spilt guts look like a heap of glistening coal.

When the creepers shook the flies exploded from the guts with a vicious note and clamped back on again. Simon got to his feet. The light was unearthly. The Lord of the Flies hung on his stick like a black ball.