There are two principle themes in Lear's angry raging in this scene, and that is the injustice of the gods and Lear's own anger at his daughters and what they have done to him. What is key to realise in this scene, which is when Lear and the Fool wander around on the storm-blasted, desolate plain, is that the weather is a powerful pathetic fallacy that serves to mirror the anger in Lear's own heart as he realises fully just how terribly his daughters have treated him:
I tax not you, you elements, with unkindness.
I never gave you kingdom, called you children.
You owe me no subscription. Why then, let fall
Your horrible pleasure.
In addressing the "elements," Lear recognises that they owe him no loyalty or kindness as his daughters should, and therefore they can let "fall" their "horrible pleasure." This is of course in contrast to his duaghters who do owe him so much and should not have treated him so disrespectfully.
Secondly, there is a definite sense in which the capriciousness of the storm and its ferocity is used to highlight the capricious nature of the gods and the vicissitudes of life. Justice is a key theme in this play, and the things that befall Lear and his daughter highlight the way that there seems to be little rhyme or reason in what happens and why it happens. The play raises massive questions about why bad things happen to good people, with the case in point being made with Cordelia. This is highlighted when Lear accuses the elements (and the gods behind them) of conspiring with his daughters against him:
But yet I call you servile ministers,
That will with two pernicious daughters joined
Your high engendered battles 'gainst a head
So old and white as this. Oh, ho! 'Tis foul.
Even though Lear stresses his age as a way of saying that the gods should not be so cruel to one of his age. Lear recognises that the gods almost treat humans as playthings rather than in a loving caring way. In such a world, there are no guarantees, and humans are left, like Lear and the Fool, to roam around on storm-blasted plains trying to protect themselves as best as they can.