If the pressure in the lungs rises above atmospheric pressure, what direction does the air move?

When the pressure in the lungs exceeds atmospheric pressure, air will naturally flow out of the lungs. This phenomenon is governed by the principles of gas laws, specifically Boyle's law, which states that when the volume of a gas decreases, the pressure increases. In the context of respiration, if the lungs contract or the diaphragm relaxes, the volume inside the lungs decreases, causing the pressure to rise above that of the outside atmosphere. As a result, air moves from an area of higher pressure (inside the lungs) to an area of lower pressure (the external environment), leading to expiration. This process is a critical aspect of normal breathing mechanics and allows for the exchange of gases, such as oxygen and carbon dioxide, in the respiratory system.