Atmospheric rivers can wreak havoc on the West Coast. These “rivers in the sky” stream enormous amounts of moisture from the tropics to western North America — double the flow of the Amazon River, on average. This moisture can produce downpours that cause widespread flood damage. From 1978 to 2017, this damage amounted to $1.1 billion per year according to a 2022 study. But atmospheric rivers are also crucial for life in California.