Meteorological Processes

Halliday (1994: 143-4):

Medium/Process: Meteorological Processes

Halliday & Matthiessen (2014: 341):

For the sake of simplicity, we represent meteorological processes such as it’s raining as having no Medium; but it would be more accurate to say that here the Medium is conflated with the Process.

Meteorological Processes: Material Clauses Without Participants

Halliday & Matthiessen (2014: 310):

This last type [construed as it + a verb in the ‘present in present’ tense] is unique in English, in that it has no participant in it.  The it serves the interpersonal function of Subject, like the there in an ‘existential’ clause, but has no function in transitivity — if you are told that it’s raining, you cannot ask What is? and the it cannot be theme–predicated (we cannot say it’s it that’s raining) or serve as an identified Theme or Rheme (we cannot say it is what’s raining/what’s raining is it). On the other hand the tense is clearly that of a ‘material’ process.  These clauses can be analysed as consisting of a single element, the Process; they are the limiting case of a ‘material’ process clause.

Meteorological Processes: Existential, Material & Relational

Halliday & Matthiessen (2014: 309-10):

On this borderline between the ‘existential’ and the ‘material’ there is a special category of processes to do with the weather: meteorological processes like it’s raining, the wind’s blowing, there’s going to be a storm. Some are construed existentially, e.g. there was a storm/hurricane/breeze/gale/shower/blizzard. Some are construed as material events, e.g. the wind’s blowing, the sun’s shining, the clouds are coming down. Some are construed as relational attributives: it’s foggy/cloudy/misty/hot/humid/sunny/frosty; here the it can be interpreted as a Carrier, since it is possible to substitute the weather, the sky or the (time of) day. Finally, some are construed as it + a verb in the ‘present in present’ tense: it’s raining/hailing/snowing/freezing/pouring/drizzling/lightning/thundering.

Why Free Indicative Clauses Require A Subject

Halliday & Matthiessen (2014: 193):

In general, every free clause in English requires a Subject, because without a Subject it is impossible to express the mood of the clause, at least in the usual fashion. We have already noted that the difference between declarative and yes/no interrogative is realised by the order of the elements Subject and Finite; and it is impossible to arrange two elements in order if one of them is not there. So while the it in it’s raining, and the there in there was a crash, do not represent any entity participating in the process of raining or of crashing, they are needed in order to distinguish these from is it raining, was there a crash.