Quick color change Question??

So I know when you have low temps the underside of the leaves tend to turn purple. I experienced this with my NYC Diesel and now its happening right out of the gate with my Silver Haze seedling. I'm just curious what the science is behind this, like why the plant needs or wants to turn purple at lower temps. Is it kinda like our cheeks getting rosey red when its cold outside?

Thanks for any info for this curious cultivator

nobody.. ?

the color has i would say 80 percent to do with the strain. then when you add the cold it will really turn. also maturity