Final answer:
The representation of Earth's gravity that includes variations such as bumps and depressions is known as the geoid. Equipotential lines depict equal gravitational potential energy, and the geoid illustrates these irregularities in Earth's gravitational field.
Step-by-step explanation:
Earth's gravity is best represented by an equipotential surface that contains bumps and depressions where areas of more or less gravity appear over the Earth. This representation is known as the geoid.
Equipotential surfaces are a conceptual three-dimensional topography that represents points of equal gravitational potential energy. When these surfaces are represented in two dimensions, they are called equipotential lines. Just like contour lines on a topographic map indicate areas of equal elevation, equipotential lines on gravitational maps serve a similar purpose but for gravity.
On Earth's surface, areas closer to sea level have higher gravitational potential energy compared to those at higher altitudes. However, due to variations in mass distribution within the Earth itself, such as mountain ranges or ocean trenches, the actual gravitational equipotential surface - or the geoid - isn't a perfect smooth shape. It has irregularities that show where the gravitational field strength varies. These variations in Earth's gravitational field are important for understanding ocean circulation, changes in ice sheets, and variations in sea level, among other geophysical phenomena.