My evergreens are turning orange

[SamClemensMT]

I have two evergreens. The fronts of these plants face the sun during the day. The backs, however are deprived of direct sunlight. The backs have started to turn orange. Does anyone know what going on here? This shouldn't be happening, should it?

 

[DancingLady]

That does sound odd to me as I grew up in a Douglas Fir forest and never saw trees do that. Do you know what kind of tree it is specifically?