Magonia by Maria Dahvana Headley

Aza Ray has been sick her whole life—breathing the air of Earth is killing her. But when she glimpses a ship in the sky, her world changes forever. Whisked away to Magonia, a realm of sky cities and storm-sailing ships, Aza discovers a truth that will rewrite everything she knows about herself. Lyrical, imaginative, and heart-wrenching, Magonia is a breathtaking fantasy about love, destiny, and the power of belonging to two worlds.