Click the picture to zoom in.
Would you recognize the pattern on this image? Well, yes, the axes are the longitude and latitude and you can see the continents, especially their industrialized subcontinents, on it.
The picture shows 17,168 weather stations across the world. You see that some regions are covered more densely than others. Mathematica 7 users have access to all the detailed current and historical weather data from these stations.
For example, you can pick a station in Florida and determine when its managers started their barbecue party last Sunday (most U.S. weather stations are cleverly attached to a grill, see wattsupwiththat.com).
The colors on the picture above don't show any temperature - just random numbers associated with the individual weather station closest to a given point. It was actually pretty easy to draw the Voronoi diagram above:
Sorry, the newest Mathematica 7 is needed.
Average temperature on Thursday (two days ago). Click to zoom in. Note that the Northern Hemisphere seems cooler. It's called "coming winter" (or "summer" in Australian English). You can see that this difference primarily affects the land.
The temperature difference between Dec 11th, 2008 minus Dec 11th, 2005. Note that it's not only the difference between the same seasons but the ENSO index was also identical at these two moments. Unfortunately, the transition to a cool PDO phase is not manifest on these land-based stations. At least, you see the Siberia getting friendlier and Canada freezing over. Click to zoom in. Globally, December 2008 is about 0.15 °C cooler than December 2005.