Fig2_4 Spring and neap tides

Fig2_4 Spring and neap tides

Fig. 2.4 . The height of the tides and the phase of the Moon depend on the relative positions of the Earth, Moon and Sun. When the tide-raising forces of the Sun and Moon are in the same direction, they reinforce each other, making the highest high tides and the lowest low tides. These spring tides (top) occur at either new or full Moon. The range of tides is least when the Moon is at first or third quarter, and the tide raising forces of the Sun and Moon are at right angles to each other. The tidal forces are then in opposition, producing the lowest high tides and the highest low tides, or the neap tides (bottom). In this diagram the height of the tides has been greatly exaggerated in comparison to the size of the Earth.

Copyright 2010, Professor Kenneth R. Lang, Tufts University