We find in at least two instances the chief god of a pantheon being replaced by the younger storm god of that pantheon. For example, in Canaanite mythology, the supreme god El is replaced with the storm-god Baal as the main god, and, in Greek mythology, Cronus is replaced by the storm-god Zeus. (Are there any more examples of this phenomenon?) Did many cults make this switch at around the same time? Is the switch to revering a younger storm god a recognized development in the evolution of religions? Have there been any studies on this topic?
The religious phenomenon has, in my opinion, this structure:
This structure is not necessarily true for every religious phenomena, here i try to draw a common line that can be followed
- A goddess, related to earth, prosperity, etc
- A god, related to sky, with all the attributes, because a god that "lives in the sky" has power over the clouds, the winds, the thunder, etc
- A younger god, as you say, sometimes the son or in a way related to the love of the goddess and the god, like the union between apsu and tiamat. The below waters and the above waters
This structure appears in different religions and religious manifestations. An important aspect of this kind of replacement, father god replaces the mother god, and the father god is replaced by the son god is very well explained in J. G. Frazer book The Golden Bough: a Study in Magic and Religion (1890) and it is a practice that belongs to matriarchal societies / beliefs. In short in a matriarchal society if a man wants to marry a woman, the man goes and establish hiself inside the woman's village.
- Woman and Man are from different villages
If there are two or more men that want the same woman, there will be a contest or a battle between them and the fittest will take her.
- Only the strongest, the fittest man can have the woman. This is a virility demonstration.
The idea is that the mother goddess needs a new husband to procreate, a new king. This process is repeated at the human scale in primitive societies and goes up to greeks and others, like Oedip.
To answer the "storm god problem": Every god related to the sky is also related to the sun, the stars, the sky phenomena, etc. All are attributes of the same god. Even if there are more complex religious phenomena and there is a god for thunder, a god for sun, a god for moon, in essence this idea is valid.
I don't know if many cults did the switch at the same time, but if we think that is a phenomen from the evolution of religious ideas around the world and this phenomen appears after another that is also verified to be a common one, yes they appear at the same time, not the chronological human time, but the religious evolution time.
I don't know if there are studies written on this topic but Frazer, Dumezil, Eliade, etc are a good start.