Tuesday, June 27, 2017

Does the Moon have a tidal effect on the atmosphere as well as the oceans?

Rashid Akmaev, a research scientist at the University of Colorado, explains.
The short answer is yes, and at various times this question of lunar tides in the atmosphere occupied such famous scientists as Isaac Newton and Pierre-Simon Laplace, among others. Newton's theory of gravity provided the first correct explanation of ocean tides and their long known correlation with the phases of the moon. Roughly a century later it was also used to predict the existence of atmospheric tides when Laplace developed a quantitative theory based on a tidal equation now bearing his name. Laplace's equation describes the motions of an ocean of uniform depth covering a spherical Earth [see illustration].
At the point on the ocean's surface closest to the moon (point A in the illustration), the lunar gravitational attractive force is strongest and it pulls the ocean toward itself. On the opposite side of Earth (point B), its attractive force is weakest, which allows the ocean to bulge outward again, in this case away from the moon. As the planet rotates from west to east the two bulges tend to stay on the Earth-moon line. (The moon also revolves around Earth in the same direction as Earth's rotation but at a much slower rate.) For an observer stationed on the surface and revolving with it, the bulges would appear as a giant wave, which follows the apparent motion of the moon to the west and has two crests per lunar day.

https://www.scientificamerican.com/article/does-the-moon-have-a-tida/

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