Heat itself does not have a specific direction or a sense of "up" or "down." Heat is the transfer of energy from a region of higher temperature to a region of lower temperature. It occurs due to the random movement of particles (atoms or molecules) within a substance.
When there is a temperature difference between two regions, the energy transfer occurs through various mechanisms such as conduction, convection, or radiation. These mechanisms operate based on the principles of thermodynamics and do not depend on any specific direction or orientation.
The direction of heat transfer is determined by the temperature gradient, which is the rate of change of temperature with respect to distance. Heat always flows from regions of higher temperature to regions of lower temperature, seeking to establish equilibrium. The direction of heat transfer is perpendicular to the isotherms (lines of constant temperature) and follows the path of decreasing temperature.
In summary, heat transfer is not influenced by gravitational forces or a sense of "up" or "down." It depends solely on the temperature difference between two regions and follows the path of decreasing temperature, driven by the objective of equalizing temperature imbalances.