For example in this episode’s poem:
天(そら)に響めく(どよめく) まやかしの
捉う心(とらうこころ)にはしる旋律(せんりつ)
For me it’s interesting that the kanji used for そら (sky/heaven) is not the usual 空 but 天 which is never read そら, usually read てん, but it conveys the meaning of heaven more than 空.
I’ve seen Bleach doing it several times in the poems
Not just bleach, just poems or lyrics and everything.
For example, 残酷な天使のテーゼ has a 宇宙(そら) in there.
Also, in Chinese 天 literally means (as is the main word for) sky, so yeah. That’s why 天気 is written the way it is.