I have rewritten the old question (below) to hopefully make things a bit clearer.
Basically I think that the temperature of the earth should be normally distributed but is not due to the ‘seasonal tilt’ and curvature of the earth’s surface. I have added some histograms for different ‘latitude bands’ of the temperatures and rainfall in mm here (I have included rainfall here but please ignore it for now). For example, [-10 ... 10] corresponds to latitude band (-)10 degrees south to 10 degrees north inclusively.
Of course temperature depends on latitude but this is due to the fact that it actually depends on seasonal tilt and curvature IMHO.
At the end of the day I am after some transformation which removes the effect of seasonal tilt/curvature to arrive at some global normal distribution for all four seasons. Does this make sense?
I have some data of the earth's surface (temperature + rainfall in mm):
Clearly the earth's tilt affects the modality/normality of, for example, the temperature distributions. I am just wondering whether there is a way to adjust for this to make the (combined?) data more normal/less modal?
I am not a statistician ... so not sure whether this is possible? Thanks in advance.