Final answer:
The diurnal inequality of a tropical/mixed tide refers to the significant difference in heights between successive high and low tides within the same lunar day, caused by the interactions of gravitational forces, Earth's rotation, and coastline shapes.
Step-by-step explanation:
The diurnal inequality of a tropical/mixed tide is a phenomenon that occurs in certain coastal areas where the tides have a significant difference in height between two successive high or low tides within the same lunar day.
This variation is primarily caused by the complex interaction between the gravitational forces of the Moon and the Sun, as well as the Earth's rotation and the effect of the shapes of coastlines and ocean basins. In a typical diurnal cycle, we might expect two high and two low tides each day. However, due to diurnal inequality in some tropical regions, the two highs and lows can differ significantly from one another in height.
It's important to note that while the twice-daily ocean tides are mostly influenced by the Moon's gravitational pull on the Earth, the actual tide experienced at any location is also affected by other factors such as the Sun's gravitational pull, friction between water and land, earth's rotation, coastline shape, and ocean basin topography. These factors result in complex patterns of tides around the world, and why tide tables are calculated specifically for each location.