Equipotential Surfaces
Gravity Equipotential
- A series of closed surfaces of constant gravity potential can be defined for all objects of planetary size
- Because objects of planetary dimensions are generally not homogenous in composition, the resulting gravity field cannot be modeled by a simple geometric description such as a sphere or ellipsoid of revolution
- The geoid is a particular equipotential surface of the Earth’s gravity field that approximates the undisturbed mean sea level of the oceans
Pressure Equipotential
- A series of closed surfaces of constant pressure potential can be defined for all objects of planetary size covered by significant gaseous layers (e.g., the Earth, or the gas giant planets)
- Because objects of planetary dimensions are generally not homogenous in composition, and the effects of rotation and irradiation may vary in time and space, the resulting surfaces of constant pressure cannot be modeled by a simple geometric description such as a sphere or ellipsoid of revolution