英语翻译Whoever has made a voyage up the Hudson River must remem

英语翻译
Whoever has made a voyage up the Hudson River must remember the Catskill Mountains. They are a branch of the great Appalachian family, and can be seen to the west rising up to a noble height and towering over the surrounding country. When the weather is fair and settled , they are clothed in blue and purple,and print their beautiful shapes on the clear evening sky, but sometimes when it is cloudless, gray steam gathers around the top of the mountains which ,in the last rays of the setting sun, will shine and light up like a crown of glory.
主要是“They are a branch of the great Appalachian family, and can be seen to the west rising up to a noble height and towering over the surrounding country. ”这句不太好懂。还有不知道翻译的朋友发现没有，前面有When the weather is fair and settled，后面有but作为转折，可后面跟的还是sometimes when it is cloudless，这cloudless不是晴朗的意思吗？这里哪来的转折啊，原文绝对没错，因为这是高考试卷上的阅读题，拜托哪位高手帮解决下，好的一定追加~~~~~~~