30%
40%

I doubt you are going to know the ans to this question, but do you have any idea as to the significance of the darker rain cloud icon on CWB? Originally i assumed it indicated a greater chance of rain, but they've listed it as 30%, while the lighter colored cloud comes in at 40%, so it can't be that. Or is it just one of those un-understandable things that you come across in our beloved Taiwan?