The passage concludes with another environmental event—something specific that reinforces the feeling of the place.
And when the wind rises it whips the sand up the beach and the white spray darts and writhes in the air like snakes of salt.
In the case of Storm Boy it’s a weather event like rising wind. Nature is such an important part of its story. The wildness of the place is reinforced by great verbs such as ‘rises’, ‘whips’, ‘darts’, and ‘writhes’.
Thiele starts this sentence with the word and which is not always recommended, but it can be used to create a kind of heightened poetic effect on the rhythm of the sentence. Imagine what the snippet would be like if started with when. It would make sense, but wouldn’t feel the same. Try starting with and to get a similar feeling.
Both are comparisons.
Look at these examples to see how each keep their theme going.
And when Summer came even the wind had somewhere else it wanted to be and the smoke and grime clung to you like an unwanted coat of paint.
And when the rains and tides meet in a dangerous way, the bay washes into the streets from the east and the wetlands ooze into the freight yards from the west, and the town sinks like a broken barge.