What influences whistleblowing ?

In what environment does whistleblowing florish ? I don't mean the kind of whisleblowing taking place in France during the second world war to settle scores with neighbors (or actually still happening now if you consider the Clearstream case). I mean the kind of moral courage needed to stand apart from a group and say "enough". Be it misbehavior or fraud. Protection of whistleblowers is certainly a factor. Also if the organisation views this as constructive and considers these people to be helping, as  opposed to branding them ratfinks, and punishing or firing them. In the public sphere, the political agenda might influence the amount of whistleblowing taking place. An article in the New York Times shows what is happening in the US as we near elections. Which raises the question of visibility - there might be a snowball effect taking place as more people follow the example of those who have divulged facts or behavior before them.