The sentence does have a very obvious subject. The environment is producing rain. The subject is the environment and its condition is being elaborated. It = environment.
The rain is not magical, the environment is producing it. The environment is raining. It's raining outside means the environment is producing rain outside.
Who could possibly confuse that as lacking a subject.
The rain is not magical, the environment is producing it. The environment is raining. It's raining outside means the environment is producing rain outside.
Who could possibly confuse that as lacking a subject.
https://www.cambridge.org/core/journals/journal-of-linguisti...