Change the brush color to black and the brush opacity to around 30%.

改变刷颜色黑色和不透明的刷到30 %左右。

youdao

When you have the brush tool selected, pressing the number keys will adjust the brush opacity.

当你已经选择了画笔工具，按下数字键可以调整画笔的不透明度。

youdao

Once we get the general area of our clouds, we want to drop the brush opacity to 20% and start slowly painting away our detailed areas.

一旦我们得到了云彩的大概区域，要将画笔不透明度调为20%，然后开始慢慢地擦除区域中不需要的细节。

youdao