Seasonal Trees check their sourrounding for the snow depth and change their appearance depending on the level. This adds more realism for gameplay in Summer or Winter Season and makes the trees appear in a more saturated green when playing in the warmer months of the year.
If you want to create your own objects with the PolarSnowlevel script. You have to build a hierarchy exactly like the one shown in the picture.
Now you have to select the parent object and add an oncreate. The oncreate should contain the following code.