This Tropical Weather Phenomenon Can Have a Big Influence on California Rain and Snow, But Key Connections Remain a Mystery

...Which is a way of saying: a lot of people ask what it takes to make it rain in California, and the answer relies on a bewildering variety of inputs, some of them very complex and very far away. One of the most intriguing, and least understood, is a weather phenomenon called the Madden-Julian Oscillation, or MJO. Chidong Zhang is featured.