Meaning: A beautiful rainbow appeared in the sky after the rain.
Choice of Words: A rainbow is a colorful arc that appears in the sky after rain. It is caused by the sun's rays shining through raindrops.
Meaning: This also means that a rainbow became visible in the sky after rain.
Choice of Words: Showed up is another way to say 'appeared'. It means to become visible or noticeable.
Meaning: This means that a rainbow was present in the sky.
Choice of Words: There was is used to describe something that exists or is present. In means inside or within something.