An exhibit on Water at the Science Museum of Minnesota contains an interactive display that allowed people to ‘become’ a raincloud. By rubbing a ‘raincloud’ tool over a series of screens displaying a topographic map, the cloud rains drops of water onto the topo-map. Visitors can see how the drops of water run down the sides of a topographic map to slow and pool together in the valleys between mountains. Colliding together, the blue drops create rivers which meander through valleys until falling off the screen.
As a fun way for visitors to interact with the exhibit, this project helps people understand how water flows (the fact being downhill- which I thought was obvious, but apparently there is an overwhelming number of people who are surprised when rivers turn to flow North instead of South, as on maps they must have an idea that gravity makes the water flow off the page.)