Weather Words: Cloud Waterfall

A cloud waterfall is a striking atmospheric visual where clouds appear to spill or cascade over a mountain ridge, escarpment or elevated terrain, resembling flowing water. Despite the dramatic look, it’s simply the movement of moist air and changing temperature that creates the illusion. These events most often occur in coastal or mountainous regions where steady winds push humid air toward higher ground.

As that air is forced upslope, it cools and condenses into tiny droplets, forming cloud along the ridge. Where this condensed moisture comes into direct contact with the terrain, it can technically be classified as fog, since fog is simply cloud at the surface. As the air passes over the crest and descends, it warms and dries, causing the droplets to evaporate. This cycle of formation on the windward side and dissipation on the leeward side gives the appearance of a continuous cascade.

Cloud waterfalls are closely tied to orographic lift, a process meteorologists monitor because it influences precipitation, visibility and localized weather patterns. While they don’t necessarily signal rainfall, they indicate stable airflow, sufficient atmospheric moisture and terrain-driven lifting, all key ingredients in mountain weather forecasting.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.