This is just a 3-dimensional plot of ozone vs temp and humidity.
In this plot, you can see that the effect of humidity on ozone
- is quite small (almost flat) for low temperatures
- is quite big (very steep) for high temperatures,
thus indicating the presence of an interaction between humidity and temperature, a fact that cannot be seen from the 2-dimensional plots.
As indicated by @mkt in his comment below, the 3D plot should indicate which side of the axes is low and which side is high, but it can be inferred from the patterns in the 2D plots.