Wind: Wind is created when hot air is replaced with cold air. The dragon has two sets of lungs. One set is gently heated by it's stomach, and the other set protects the air inside from heat. As it attacks it sends quick bursts of air from each set of lungs. the pattern would be: Hot, Cold, Hot, Cold, etc. Those bursts in that pattern would generate violent winds at increasing speeds. The speed of the wind can be changed by the amount of air being released from the lungs and the pattern being changed.
Water: Water is H2O. The Hydrogen and methane produced from the digestion process fills the flight bladder and is heated at the same time. If the Dragon inhales, the CO2 produced from the lungs is transported to a gullet like sack, then the hot gas is released into the gullet like sack to mix with the CO2. That mixture is then ignited by a chemical that is produced from a gland in the gullet like sack. That ignition rips the CO2 apart and the Carbon is absorbed into the dragon's body to increase body mass and the Oxygen combines with the Hydrogen that is heated even more from the igniting of the Methane gas, to create H2O(AKA: Water). it then squirts the water like a SuperSoaker out the mouth. The only down side is it takes a while to generate enough water.
Storm/Cloud: This dragon has the capability of the Lightning Dragon but it also has the capability of the Water Dragon. it uses the water from the gullet like sack to mist the air forming fog and then uses the
heat energy from the lightning to turn the fog into water vapor that then condenses into clouds.
Ice: Fish have a cool(hehe, a pun for the topic of Ice) protein the prevents them from freezing solid in the winter. The Ice dragon has a more evolved form of that protein, that allows them to regulate the temperature of the air that it stores in a separate set of lungs. The regulation of the air temp, happens when the proteins basically "Suck" all of the heat from the stored air to not only prevent the separate set of lungs from freezing but also to help heat the Dragon's body, so that it can survive in the harsh subzero climate of the frozen landscape it lives in. It then uses the air that is supper cooled and the water from the water producing organ system that the Water Dragons have, to either create super chilled mist that can freeze an object solid and/or create physical ice.