In particular, you can provide some links to that site that provides contour plots of weather data, although I found those examples a bit to complicated to be useful immediately. Perhaps a specific example could help a reader make more use out of that data set, in particular, the time series that are supposed to be available.
With respect to the Dandelin page, can you isolate the place where the argument breaks down for you? I wonder if an interactive illustration would clear up the difficulty. If you have access to a UNIX machine in the CS department, you might be able to run the fnord program. In any case we should be able to run it in the class, if everything begins to work there.