我就知道国内判定绿蓝黑度数比国外低

北美标准是
Green circle Easiest The easiest slopes at a mountain. Green Circle trails are generally wide and groomed, typically with slope gradients ranging from 6% to 25%(a 100% slope is a 45 degree angle).
Blue square Intermediate Intermediate difficulty slopes with grades commonly ranging from 25% to 40%.These slopes are usually groomed. Blue Square runs make up the bulk of pistes at most ski areas, and are usually among the most heavily trafficked.
Black diamond Difficult Amongst the most difficult at a given mountain. Black Diamond trails tend to be steep (typically 40% and up) and may or may not be groomed, though the introduction of winch-cats has made the grooming of steep slopes both possible and more frequent.
Double black diamond Expert These trails are even more difficult than Black Diamond, due to exceptionally steep slopes and other hazards such as narrow trails, exposure to wind, and the presence of obstacles such as steep drop-offs or trees.

double black diamond一般有蘑菇等不一定比一些black mode的抖但是难