WEATHER

A number of WEATHER verbs—notably rain, snow, hail and thunder—effectively have no semantic roles at all. The verb makes up a complete clause, but the impersonal subject it has to be added, to satisfy the requirement of English syntax that each clause have some constituent in the subject slot, e.g. It is raining, It snowed in the night, Listen to it thundering out there.

It is possible to include with a WEATHER verb an NP that contains a cognate noun, e.g. It thundered the most ear-splitting cracks of thunder that I’ve ever heard, or a noun that is a near synonym of the cognate noun, e.g. It rained an absolutely tremendous storm while we were on holiday. The ‘cognate’ NP is not properly either an object or an extraposed subject in such clauses—it is just an appositive mechanism for commenting on the nature of the weather event. As was noted above, when discussing cognate NPs with CORPOREAL verbs, there are much wider possibilities for modification of a noun in an NP (by adjectives, etc.) than there are for adverbial modification of a verb (e.g. we could not say *It thundered ear-splittingly, or *It rained (absolutely) tremendously).