That's a very good question there. At first I thought that maybe this is some sort of tropism or growth response under the influence of the Earth's magnetic field, however I forgot about the fact that the angle changes proportionally to the increase in latitude, which basically means two things for me: a) it's probably the result of the combination of different factors (as you rightly pointed out), and b) there are definitely variables we ignore (again).
In conclusion, I'm not sure! This is only a theory I just came up with to satisfy my ego. :P
Whatever the cause, the results are a beautiful mystery...
Couldn't agree more!
Keep up the awesome work!
I guess we'll have to wait and see what the final verdict has to tell us.
Thanks for the encouragement! :D