This is all good work, as far as it goes.

To improve it, remember that temperature is directly correlated with altitude, so you'll want to add a variogram for elevation (and of course you'll need many, many more measurement points).

The second improvement would be to use the Haversine function instead of the Euclidean distance between points, because we're dealing with a globe, not a flat surface.

And of course the plot itself should really be using an equal area projection suitable for the 46°N to 49°N latitudes.