These are a few of the figures I created in the last year of my PhD to represent variation of a single quantity with variations in two other continuous variables. The y-axis contains a break between 10-20 and 10-2 as there was no data there. Several of these map graphs have been created to check the variation with a third variable in a discrete way (not continuous), and displayed together in a single figure. This was done to more easily spot trends in the large amount of data that resulted from the parameter study I performed.
In this figure, the colors represent temperature. The color scale is deliberately kept discrete (as opposed to a smooth gradient), so that contours are visible even when not explicitly marked with a black/white contour line. This makes it easier to estimate a value for the temperature in a certain point.
The figure below shows variations in the polytropic exponent. The important thing to know is that a transition in physical behavior is expected to occur around a value of 1. Therefore, the color scale is chosen in such a way that it’s easy to spot values well below (white-green), well above (pink-black), and around 1 (blue). The pointed ends of the color bar indicate that there were additional values below the set minimum and above the set maximum, but we can get away with lumping them together with the min/max values as we mainly care about the transition around 1.
The figure below shows the ratio between two heating rates, using a diverging color scheme centered on 1, where they are both equal. The green/pink color scheme makes this figure colorblind-friendly, unlike green/red schemes (which would perhaps have been somewhat more intuitive, due to the connotations green=good and red=bad).