Translation:Sometimes after the rain there is a rainbow.
Sorry, the Polish sentence is factually incorrect.
I'd accept "Sometimes with the rain there is a rainbow" - but that doesn't translate po. A rainbow needs Sun and rain (or other water droplets, e.g. a waterfall) at the same time: it's simple school physics.
Of course, it might have stopped raining where I am: if it's still raining somewhere between me and the Sun, I'll still see the rainbow.
Not about his question but this topic of nature geerally, I ws looking forward to broadening my knowledge of nature vocabulary but s far the exercise has been taken u with difficult grammar like which case follows which preposition. Please increase vocab content and reduce grammatical niceties