Once the map is created, changing the projection, colors, and area of view becomes trivial. There are many ways to estimate it at points were no observations exist. The answers you get with each method may differ markedly. Here, the results of one method are displayed. I can then try other methods, and compare the results both graphically and numerically.
Units are percentages.
We often look at monthly or annual totals of precipitation. This map illustrates the number of days, on average, in which it rains in each of the two months. One can then compare this maps with a precipitation map to see which regions get very intense rains on few days, and which get a bit of rain continuously. Digital elevation data were obtained by sampling from topographic maps. As with the map of Baffin Island above, it is not difficult to change the projection, the color pallet used, and other map features.