Vertical tide generating forces are the components of the overall tide generating force that act perpendicular to the Earth's surface.
The Nature of Tide Generating Forces
According to the reference, the tide generating force is the sum of gravitational and centrifugal forces. These forces arise from the gravitational pull of celestial bodies, primarily the Moon and the Sun, and the centrifugal force resulting from the Earth-Moon and Earth-Sun systems revolving around their common center of mass.
The reference highlights that in revolution without rotation, the centrifugal force is the same for every point on the earth´s surface, but the gravitational force varies. This difference in gravitational attraction combined with the uniform centrifugal force creates the differential force known as the tide generating force, which acts across the Earth.
Components of the Tide Generating Force
The total tide generating force vector acting at any point on the Earth's surface can be mathematically broken down into two main components:
- Horizontal (Tangential) Component: This part of the force acts parallel to the Earth's surface. It is the primary driver of tidal movements, pushing water horizontally across the globe to create tidal bulges and currents.
- Vertical (Radial) Component: This part of the force acts perpendicular to the Earth's surface, either vertically upwards or downwards, depending on the location relative to the celestial body (Moon or Sun).
Understanding the Vertical Component
The vertical tide generating force is specifically the portion of the tide generating force (which, as per the reference, is the sum of gravitational and centrifugal forces) that is oriented directly towards or away from the center of the Earth at a given location.
While this vertical force does slightly alter the local force of gravity and can cause a tiny change in the apparent weight of objects, its effect on the large-scale movement of water is generally much less significant compared to the horizontal component. The horizontal component is most effective at points about 45 degrees away from the point directly under or opposite the celestial body, while the vertical component is strongest at the point directly under and opposite the celestial body, acting radially outwards at those points.
| Tide Generating Force Component | Direction | Primary Influence on Tides |
|---|---|---|
| Horizontal (Tangential) | Parallel to surface | Generates tidal bulges and currents |
| Vertical (Radial) | Perpendicular to surface | Slightly modifies local gravity; minor direct influence on tidal flow |
In essence, the vertical tide generating force is the perpendicular part of the total tide generating force described by the reference, which is the combined effect of gravity from celestial bodies and the centrifugal force of the Earth's orbital motion.
