The Sun is of course a very important factor when it comes to temperature. Unfortunately, the De Bilt dataset from the KNMI is missing a lot of data concerning the Sun's radiation. The data is given in Joule per square centimeter. There are also other variables in the file, which are derived from solar radiation, such as the sunshine duration in hours.

We are going to analyze the radiation data a bit, draw a histogram, and compare it with the daily average temperatures. To compare, we will calculate the correlation coefficient between radiation and temperature and plot yearly relative changes in average temperature and radiation. Originally it seemed a good idea to have a scatter plot, but that didn't look right with thousands of data points, so instead, it was decided to compress the data as it were. Later, the author realized that radiation was present from around 1960 onwards, so it might have been better to plot the correlations coefficient...