Introduction to Tides
The periodic rise and fall of sea level, known as the tide, is caused by the gravitational interactions of the Moon and Sun on the oceans of the Earth. While gravity provides the driving force, the rotation of the Earth, the size and shape of the ocean basins and local coastal circumstances ultimately determine the magnitude and frequency of the tide at a particular place.
This section provides a basic understanding of tidal theory and a description of tidal phenomena pertaining to New Zealand.
The cause & nature of tides
Tide-generating forces, the tidal bulge, factors affecting the position, direction and size of tidal bulges, what happens when two tidal bulges interact with one another, spring and neap tides explained, the equilibrium theory, how the shape of the land affects tidal bulges. more...
Tides around New Zealand
The nature of New Zealand tides, spring and neap tides, how the tidal bulge moves around New Zealand, duration of New Zealand tide cycles. more...
Analysis & prediction of tides
Methodology for predicting tides, factors affecting accuracy of tidal predictions. more...
Meteorological effects on tides
The effect of barometric pressure and strong winds on sea level height, an explanation of storm surges. more...
Making sea level measurements
Current and past technologies for measuring sea levels, how tides are measured against a local datum. more...
About tidal streams
Explanation of tidal streams, flood stream, ebb stream and slack water.more...
Definitions of tidal terms
Get definitions for terms relating to ports and tidal levels. more...
