Both are correct.
The second one compares the sky before and after a heavy rain.
The sky is blue after a heavy rain or the sky is bluer after a heavy rain .
Which one is correc
2 answers
or, it could be comparing the sky after a heavy rain to the sky after a light rain.
Or other stuff. But it still could be grammatically (if not actually) correct.
Or other stuff. But it still could be grammatically (if not actually) correct.