I have seen trout jump completely out of the water on occasion too, but mostly they do a surface roll over. What the conditions are that make the difference I have no ideas.
But let me post again something that I have experienced that's kinda related that I consider spectacular. My trout fishing is in the mountains and it's a considerable drive from where I live over here on the coast and I don't get up there as often as I'd like. Around home is warm water fishing .... two good sized rivers, and a lot of marl pits that were dug out for base in doing road construction, kinda the same as gravel pits. Also on rare occasion do some salt water fishing (in the salt water marshes). But back to warm fresh water fishing, the usual fare is L/M bass, crappie, and bream (bluegill). This occurrence happens usually while fishing the marl pits using a popper (although it happened one time using a Goddard Caddis fly) - having a L/M bass break completely out of the water and snatch that popper (or the fly) in mid air before it ever reaches the water surface!