Kinetic temperature plotted against the logarithm of the NH₃ column density. Northern ATLASGAL sources are shown in black and the southern sample in red. For the contour plot in the upper panel, we counted the number of sources in each column density bin of 0.5 dex and in each kinetic temperature bin of 3 K. The contours illustrate 10% to 90% in steps of 10% of the peak source number per bin. These levels are shown in all contour plots in this article.