"Greeting the Sun" is a ritual, performed every morning (weather permitting), where dragons rise into the air just before dawn, and let the first light of the sun shine on them as they dance in the air.
It isn't a formal, choreographed thing, but rather pure exuberance in the act of flight, and in being Dragon.
For Tahiru, it's a rare chance to put aside all the things weighing on his mind, and to just live in the moment.
It's also for those watching from the ground. If you don't have wings of your own, let your heart fly with him for a little while.