A method of reducing the amount of water in a region of air including: forming seed ice crystals; dispensing the seed ice crystals towards the region of air; allowing water in the region of air to freeze or deposit onto the seed ice crystals; and allowing the resulting ice crystals to move from the region of air so as to reduce the amount of water in the region of air. An ice crystal seeding assembly arranged to reduce the amount of water in a region of air, the seeding assembly includes an ice crystal seeder and dispensing means, the dispensing means being arranged to dispense seeded ice crystals towards the region of air so that water in the region of air freezes or deposits onto the seed ice crystals and that the resulting ice crystals move from the region of air.