The Obelisk.

The obelisk posture it seems,is an excellent way for a dragonfly to cool down on a very hot day. Favoured mainly by dragonflies that  spend a lot of time on some sort of perch  waiting for a meal to come by, a dragonfly will raise its body to a vertical position.This ensures that they cast as little shadow  as possible and therefore the suns' heat is minimized.

I think that this behaviour is not likely to be seen too often  in the UK, as temperatures rarely rise high enough.In hotter climates however it is a common sight.