Prolonged droughts, wildfires and water shortages. Torrential downpours that overwhelm dams and cause catastrophic flooding.

Here’s what experts say. Water constantly moves between the Earth and its atmosphere. But that system — called the hydrological cycle — is speeding up as global temperatures get hotter ...

Water does all this without leaving Earth. Its quantity is virtually constant. The main processes involved in this cycle are evaporation, plant transpiration, condensation, precipitation (rain and ...