The phrase "sit tight" suggests human endurance, patience, and determination. It shows the islanders are holding their ground, not fleeing or panicking.
The verbs "dives" and "strafes" are aggressive, military terms usually used to describe attack planes. This personifies the wind as a violent attacker, emphasizing the storm’s ferocity and unpredictability.
The adverb "invisibly" adds to the menace by highlighting the unseen, unpredictable nature of the wind, increasing the tension and fear.