“on cloud nine”不是指“在九霄云上”，其正确的含义是高兴极了；异常兴奋；乐不可支。

【例句】
When Michael was born I was on cloud nine.
迈克尔出生的时候，我乐不可支。

Ever since Mary got her promotion at work, she's been on cloud nine. I don't think I've ever seen her happier!
自从玛丽升职后，她非常高兴。我觉得我从来没见她那么高兴过。