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The Sun similarly causes tides, of which the theoretical amplitude is about 25 centimetres (9.8 in) (46% of that of the Moon) with a cycle time of 12 hours. At spring tide the two effects add to each other to a theoretical level of 79 centimetres (31 in), while at neap tide the theoretical level is reduced to 29 centimetres (11 in).
The Mediterranean Sea had two high tides and low tides, though Galileo argued that this was a product of secondary effects and that his theory would hold in the Atlantic. However, Galileo's contemporaries noted that the Atlantic also had two high tides and low tides per day, which led to Galileo omitting this claim from his 1632 Dialogue. [27]
Figure 1: Tidal interaction between the spiral galaxy NGC 169 and a smaller companion [1]. The tidal force or tide-generating force is a gravitational effect that stretches a body along the line towards and away from the center of mass of another body due to spatial variations in strength in gravitational field from the other body.
Such weather-related effects on the tide can cause ranges in excess of predicted values and can cause localized flooding. These weather-related effects are not calculable in advance. Mean tidal range is calculated as the difference between mean high water (i.e., the average high tide level) and mean low water (the average low tide level). [2]
Body tides also exist in other astronomical objects, such as planets and moons. In Earth's moon, body tides "vary by about ±0.1 m each month." [11] It plays a key role in long-term dynamics of planetary systems. For example, it is due to body tides in the Moon that it is captured into the 1:1 spin-orbit resonance and is always showing us one side.
As you might expect, the moon is involved. But we’ve made it worse.
Atmospheric tides are also produced through the gravitational effects of the Moon. [4] Lunar (gravitational) tides are much weaker than solar thermal tides and are generated by the motion of the Earth's oceans (caused by the Moon) and to a lesser extent the effect of the Moon's gravitational attraction on the atmosphere.
Munk & Wunsch (1998) estimated that Earth experiences 3.7 TW (0.0073 W/m 2) of tidal heating, of which 95% (3.5 TW or 0.0069 W/m 2) is associated with ocean tides and 5% (0.2 TW or 0.0004 W/m 2) is associated with Earth tides, with 3.2 TW being due to tidal interactions with the Moon and 0.5 TW being due to tidal interactions with the Sun. [3] Egbert & Ray (2001) confirmed that overall ...