Why is there storm clouds above my villagers heads? [closed]

Solution 1:

From the wiki this particle indicates that the villagers are upset. In this specific situation, it is because they cannot successfully breed, due to a shortage of resources (e.g. beds):

Attacking a villager in a village; when villagers can't breed because there aren't enough beds nearby.

In older versions, this requirement still applies - villagers are limited to whatever number of "resource" they require in order to breed - in older versions (as BlueTangsRock mentions) could be either doors, or a minimum amount of food per villager, in order to successfully breed. E.g:

12w07a: Villagers now repopulate villages by the number of houses there are.

Source