How can I force a dragon to engage in combat?

If you are near a village, farm, etc. go to it. If you are quick enough then the dragon will most likely attack the village instead of flying in an annoying circlular loop. You could also try to get it's attention by shooting it with a arrow... To the knee xD

If you have good aim and long range, you might be able to hit it with an arrow or a spell, but I typically can't force dragons circling high in the air to land.

Later in the main quest, you get a more direct solution to this that I won't spoil, but by that point, every dragon had murder on its mind when it flew near me.