Question

water in a closed tube is heated with one arm vertically placed above an arc lamp. will the water begin to circulate along the tube in the clockwise direction?

Answer 1

yes it starts circulating because it starts heating up.

Answer 2

Water will circulate in the clockwise direction. The molecules immediately above the arc receive heat by conduction. They rise up and get replaced by cold molecules from the right side. This will make the water circulate in clockwise direction.