Hotter air can hold more water. In cooler climates, the air over a region will become saturated with moisture, causing precipitation. In warmer climates, the ai

Hotter air can hold more water. In cooler climates, the air over a region will become saturated with moisture, causing precipitation. In warmer climates, the air is able to hold a lot more water before becoming saturated, therefore the rain falls somewhere else. I imagine you'll get more rainfall over oceans; air currents over land will hold onto moisture until they blow over oceans, cooling them. I also imagine you'll get more rainfall on the sides of mountains which are already regions where warm, damp air rapidly cools causing precipitation. Please don't take this as truth, I'm just theorizing, I'm not qualified.