Ocean and atmosphere layers and the Flat Earth Society

This is Navy modelling of an extremely difficult parameter, Evaporative Ducting and yes the scale is feet. Direct linking to these mil.gov maps via https is not possible, so try this https://www.fnmoc.navy.mil/wxmap_cgi/index.html

Flat Earth anti-proof is at the end, skip too much, it won’t make sense.

Water evaporation leads to a distinct air layer close to the surface where the boundary with air above is a change in refractive index. This forms an EM wave duct (as in channel). For shipping this is of critical importance since a radar set within the channel will suffer distortions, therefore the height (depth above sea level) of the duct is critical for shipping.

The official text is not public so from Google bot cache

Evaporation Duct Height
Description

The evaporation duct height (EDH) is associated with the sharp drop in moisture immediately above a water surface and is given by the height in the surface layer where the gradient in modified refractivity (M) changes from negative to positive. EDH values can vary from a maximum value of 40 m to very low heights near zero depending upon the stability, sea surface temperature, wind speed, and relative humidity. COAMPS computes the EDH on a special high-resolution vertical grid (1-m spacing) using surface similarity theory. These expressions can be problematic for both light winds and stable surface fluxes. Under those conditions, the near surface M-gradient can be quite weak and a specific EDH value difficult to determine. — http://www.nrlmry.navy.mil/refract/evapductht.htm

Methodologically and climatically this is a warning about complexity of water surface evaporative conditions, is not evenly spread. Water vapour is critical to radiative.

Optically there are effects and there are various distinct layers under various conditions. To a degree I expect much the same over damp land.

My interest in this came from a comment made on WUWT by the venerable Tim Ball writing of his navy experiences with sonar, acted as a reminder of some of what I have long forgotten.

He recounts how anti-submarine listening devices dropped from the air could be fooled by acoustic ducting, a submarine very close was silent but hundreds of km away could be heard. A voice of actual experience.

The WUWT comment is here

We know there are atmospheric layers but there tend to many more under some conditions where I am raising this to raise awareness of the complexity and how a wealth of data is waiting in radio propagation archives.

Here is one page of a radio propagation tutorial written by Dr. M.J Willis, BSc, PhD, MIEE CEng (personal bio)

The Fundamentals: Beyond the Horizon

There is a lot more reading in the tutorial if you have the time, a mountain of information, a lot pertinent to the atmosphere and climate science. Link to the whole lot is on Propagation from the site home page.

Much more can be found on the net.

For amusement lets turn to the Flat Earth Society

Lets look at some of their evidence where perhaps the reports are factually accurate!

For those with network speed and good eyesight
“Experimental Proofs (With Illustrated Engravings) That the Surface of Standing Water is Not Convex But Horizontal”, Samuel ‘Parallax’ Rowbotham, 1870 [PDF 4.7M]

Short versions of similar observations can be found on the FES wiki
http://theflatearthsociety.org/wiki/index.php?title=Experimental_Evidence

I have a suggestion, it was indeed observed, optical ducting above the water. Notice ” The sun was shining strongly upon them in the direction of the south-southwest; the air was exceedingly still and clear, and the surface of the water smooth as a molten mirror, so that everything was favourable for observation.”

Flat Earth evidence was a mirage.

Tim