I feel it in the earth. I smell it in the air. Much that once was 4th Edition is lost, for none now live who remember it.
Alchemically, Water+Earth = ice could work. Water is cold and wet, Earth is cold and dry. But where does that take us?
Earth and Fire are both Dry, but they can be hot and cold. Metal is dry, and it can be hot and cold. Metal is forged from ore, refined with heat. So it can work.
Air and Fire are both warm, but what is warm and also wet and dry? Thunder storms are usually hot and humid, so that works.
Air and Water are both wet. What is wet but also warm or cold? Clouds, steam, mist, weather, rain could all work.
My own personal 8 elements are this, though: Air, Lightning, Fire, Metal, Earth, Wood, Water, Ice, and back to Air.