In convection why does the hot fluid rise in the center and the cold gas fall on the sides?

The hot liquid or gas is less dense than the liquid or gas in cold areas, so it rises up in the center.

The denser cold liquid or gas falls to the sides because of it’s density.

small = small current large mag large current

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.