Talk:Atmospheric tide

Fourier Analysis - obviously nonsense
The main section explains the 12 hour component of atmoshperic thermal tides by stating that a fundamental with 24hr period is a squarewave and is rich in harmonics. This, it is said, creates a 2nd harmonic with a period of 12hrs. However, most schoolboys know that a square wave has odd harmonics only, so this cannot be a valid explanation for a component at 12hrs. Moreover, this reference describes a 12hr period only:-

http://weather.mailasail.com/Franks-Weather/Atmospheric-Tides

with no mention of a 24hr component. Could comeone clarify this, and remove the reference to the 2nd harmonic of a squarewave, which is obvious nonsense that almost anyone will recognise as such. --82.32.49.157 (talk) 18:35, 13 March 2011 (UTC)

Agreed: a square wave representation of the day-night cycle of solar heating would have no semidiurnal (twice a day) harmonic, or any other odd harmonics. I think this mistake could be fixed by simply replacing "square wave" with "rectified sine wave" in the text. A rectified sine wave is a better approximating to the solar heating function than a square wave, and it has both odd and even harmonics. Of course the text should also note that the diurnal (once a day) harmonic is the primary component of the forcing.128.115.184.106 (talk) 21:44, 30 December 2013 (UTC)Curt Covey, PCMDI / LLNL

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Side view
A diagram showing the Earth from the side and how the shape of the atmosphere varies would be very helpful. -- Beland (talk) 19:00, 12 September 2019 (UTC)

Amplitudes 60 and 120 hPa, or just Pa?
The current article text contains:

"The fundamental solar diurnal tidal mode which optimally matches the solar heat input configuration and thus is most strongly excited is the Hough mode (1, −2) (Figure 3). It depends on local time and travels westward with the Sun. It is an external mode of class 2 and has the eigenvalue of $ε −2 1 = −12.56$. Its maximum pressure amplitude on the ground is about 60 hPa. The largest solar semidiurnal wave is mode (2, 2) with maximum pressure amplitudes at the ground of 120 hPa. It is an internal class 1 wave. Its amplitude increases exponentially with altitude. Although its solar excitation is half of that of mode (1, −2), its amplitude on the ground is larger by a factor of two. This indicates the effect of suppression of external waves, in this case by a factor of four. "

I have no access to the source mentioned.


 * But in https://journals.ametsoc.org/view/journals/atsc/68/3/2010jas3560.1.xml I see mention of measurements revealing amplitudes on the order of 100 Pa for semidiurnal atmospheric tidal waves in Jakarta, Indonesia (formerly Batavia).
 * And on https://www.buienradar.nl/nederland/weerbericht/weergrafieken/6290 [Meetstation Twente, 2022:03021] I see an earth surface atmospheric pressure graph showing what may be a semidiurnal tidal wave with an amplitude of approximately 100 Pa as well in Enschede, the Netherlands.

Therefore, and since 100 hPa is equivalent to no less than approximately 10% of the average atmospheric pressure at sea level of around 1,013.25 hPa (only the strongest hurricanes reach surface pressures less than 900 hPa), I wonder if the amplitudes 60 hPa and 120 hPa mentioned in the article are actually meant as 60 Pa and 120 Pa.Redav (talk) 01:47, 22 March 2022 (UTC)