Tidal Forcing
The larger of the periodic gravitational forcings is from the Moon but that of the Sun is also important. The images here show lunar tidal forcing when the Moon appears directly over 30° N (or 30° S). This pattern remains fixed with the red area directed toward (or directly away from) the Moon. Red indicates upward pull, blue downward. If, for example the Moon is directly over 90° W (or 90° E), the red areas are centred on the western northern hemisphere, on upper right. Red up, blue down. If for example the Moon is directly over 90° W (90° E), the centre of the red area is 30° N, 90° W and 30° S, 90° E, and the centre of the bluish band follows the great circle equidistant from those points. At 30° latitude a strong peak occurs once per lunar day, giving significant diurnal forcing at that latitude. Along the equator two equally sized peaks (and depressions) are equally sized, giving semi-diurnal forcing there.
Read more about this topic: Earth Tide
Famous quotes containing the words tidal and/or forcing:
“And now it is once more the tidal wave
That when it was swept by, leaves summits stained.
Oh, blood will out. It cannot be contained.”
—Robert Frost (1874–1963)
“If we consider what happens in conversation, in reveries, in remorse, in times of passion, in surprises, in the instructions of dreams, wherein often we see ourselves in masquerade,—the droll disguises only magnifying and enhancing a real element, and forcing it on our distinct notice,—we shall catch many hints that will broaden and lighten into knowledge of the secret of nature.”
—Ralph Waldo Emerson (1803–1882)