Have a look at the annual and daily precipitation of Wapato, a town located on the Yakama Indian Reservation. It is an agricultural community that specializes in apples and potatoes. Farming there relies on irrigation because the climate is arid. Rain falls only 38 days a year on average, and of those days only 29 inches of rain fall, on average. The most rain in one day was 2.3 inches, on November 11, 2009.

Applying a data smoothing filter to the precipitation chart produces a serendipitous effect: it looks like the surface of water! The tip of each wave represents a day when it rained. Move your mouse cursor over the chart to see individual precipitation measurements. Each data point represents one day of precipitation. The chart can be rotated, and it is possible to zoom in and out.

Viewing the data with a data smoothing filter has an averaging effect, so that the values are smaller than in actuality. To see the actual recorded values for each day, view the chart as a heat map with smoothing turned off.