This page shows the global average precipitation (rain). On this page you can find two kinds of visualizations. The first one shows an animation that shows the precipitation for each month of the year. The second one is a static image showing the global annual average precipitation.
These images were created using open global precipitation data from the www.esri.noaa.gov site. The data was downloaded in NetCDF format and I converted it using a simple java program to a list of CSV files for easy processing in javascript. From these CSVs I used the HTML5 canvas to create these images. This page only shows the images, not the canvas elements. The reason is that the CSVs are rather big. For more information on how this was done, look at this article on the smartjava site.
When you take the amount of precipitation for each month, and divide it by the amount of months you get a general idea where the most rain falls in a year. Of course the sahara and the middle-east stick out, but apparently also chili is a bit dry. Which apparently is called the Atacama Desert and is one of the dryest places on the earth.
The same scale, shown below the image, applies here as we've used for the previous series of images.
