Differential Refraction



Another way to determine the state of heat of the atmosphere.

Always avoided for fear of navigation anomalies, differential refraction or the degree of flatness exhibited by the sun is a great thermometer for the entire sky at once. [Correction here]. The lower limb of the sun always has lesser refraction than the upper limb (except near the equator). Near horizon thick red perimeters on bottom of sun disks appear wider vertically than blue at the upper limb, this is caused by various optical artifacts especially by digital cameras infra red sensitivity. (Feb 27, 2010).

EH2r has proven on many occasions the effects of cold dense air which creates greater refraction (2010: inversions theoretically should reduce sun disk sizes dramatically, but rarely was this captured in a comprehensive way, comparing Montreal differential refraction summer captures with winter Resolute Bay ones has confirmed the cold vs warm differences remarkably well). In all cases of sun observations, the sun image is never really entirely round except when it is very near Zenith (90 degrees elevation). The lower limb is never really round, but unless you have optical filters and lenses, it is rarely noticed except during EH2r circumstances. 2002, 2003 insert: there has been some recent data coming out from lower latitudes which confirm a wider range of differential refraction results than previously expected, D.F. intercomparisons is a nascent science, I expect several new discoveries which will change our understanding of our atmosphere radically. Insert 2010: wide unsuspecting variances in vertical sun disk dimensions may happen with shots a few minutes apart, this suggests the atmosphere is stacked with river layers of air, which changes almost continuously. This is true for most elevations. Blue upper limbs can be captured well above 20 degrees elevation. Green flashes were captured with the sun more than 4 degrees above the horizon. Sunspots may oscillate vertically along the air waves....






[dm011839c] The outline is a perfect circle, a March 01 sun disk image at +7.85 degrees elevation,
as you can see, is not really round at a modest elevation. dV equals the vertical diameter in minutes
calculated from the dimension of the horizontal diameter measurement assumed to be 32’ of arc
.



A simple way of determining total atmospheric average temperature would be to take sun differential refraction readings during a daily transit. Modern spectrometers modified with image specific software can do the job nicely. In essence a compressed sun indicates a colder total average temperature of our atmosphere. A nice round sun, with little or no compression implies a warm average.

Measuring Differential refraction is made quicker by taken pictures with a CCD camera, although organizing a proper filter was difficult, after many tries I made one which appears to have given satisfactory results. Another hindering factor is of course clouds. Which have nullified many a days of observation. But as with all things, a hinder can be in fact a new way of measuring refraction, it is now quite certain, thin clouds do not affect very much refraction readings. It is also true for a few more cloud formations with particular sun angles, but distortions prevail in most circumstances when there are more than one cloud deck with individual or combined cloud shapes which create great illusions.





[dm261439] Very thin clouds do not seem to affect total refraction in a great way. This picture
confirms the visual measurement within 0.2 minutes of arc. Compression compares well with a
similar observation done without any clouds (see below).



The existence of EH2r stems in part from the old Cook versus Peary debate. Whereas Dr Cook’s contentions of achieving the North Pole by way of land was always denied by most historians, while the opposite is maintained for Peary. Some of the work done below proves that historians judged Cook too rapidly while never really analyzing Peary’s data. Peary’s differential refraction at the pole was a mere 10 seconds of arc April 8, 1909, while Dr Cook’s differential refraction at the same time of year varied from 6 to 6.5 minutes of arc in 1908. Looking at the data below easily proves Peary’s data as unobservable. Dr Cook’s compression of the sun disk image is theoretically possible, he observed the sun with about 5 atmospheres and a surface temperature of –31 to -44 F, a great deal of cold air. Still similar to extreme compressions has seen below have not been recorded at 10 degrees elevation. Keep in mind that February and March 2002 upper atmospheres over Resolute Bay were warmer than usual. Nevertheless, an extremely cold atmosphere is needed for comparisons tests, was it so cold then?


2003 Post Script: A consistent 10 arc second compression between 6 and 7 degrees elevation is still un-repeatable. This renders Peary's observations at the North Pole very much questionable. While an extremely severe sun compression between 9 and 10 degrees elevation as measured by Dr Cook has equally not been repeated. A distinction should be made though, while very cold air sun disk measurements have to wait, again, another season, 10 Arc second compressions by Peary can not be explained in terms of an event found in nature, extensive data done all over the world can attest to this. For Peary to be vindicated, a similar observation must be made somewhere in the World first. Then one must accept Peary's data only if a 10 Arc second sun compression at 6.5 degrees can be repeated near the Poles, it would be good for Peary believers to come up with such a measurement, data is more convincing than insults. Recorded multiple Polar observations are rare, it seems that more observations is the only way to establish a permanent closure to a near 100 year old argument. Severe vertical compressions of the sun disk at relatively high elevations have been measured in 2002, this phenomenon was seen again on a few occasions in 2003. The opposite, severe expansions, was never measured to date, I know of no database which replicates Peary's observations. During warmer Polar air profiles, refraction values acquired here became very similar to what was expected by refraction tables found in Naval Almanacs. However, Peary's North Pole sun disks were always compressed by 10 Arc seconds, defying nature itself (no two measurements can have identical compressions, check out the data to the left) and Naval Observatory tradition. A round sun disk as measured by Peary in 1909 can only be seen at about 15 to 20 degrees elevation. Unlike Peary, Dr Cook's data contradicted the tables but did not defy nature, he never had two identical compressions. Measuring sun dimensions during a very cold atmosphere will help determine if there are such things as extreme compressions. But work on this matter is not easy, it is a question of patience, hard work and luck. So far, from the data acquired in Resolute, it is unlikely that the sun can be compressed by 6 minutes of arc at 10 degrees elevation. A full sweep of Polar observations has just begun, surprises are usually the norm in Nature, my work is just the tip of a really big iceberg. WD June 2003.


2004 Post Script: It appears certain Peary’s consistent 10 Arc seconds compressions are beyond belief, totally impossible and out of range of a 20 Arc second measurement error. A picture allegedly taken by Peary himself at the "Pole" shows a much flatter sun then measured. Peary apologists, keeping up their impossible defense of such fraudulent abominations, are in the same boat, they will defend their sunken beliefs, fantasies at best, till ignorance thrives no more. Dr Cook, on the other hand, looks better and better, despite similar doubts expressed by myself, a reference proclaims actual very shrunken sun, ‘ellipsoid’ sun, observed by astronomers, at Cook’s sun elevation. Excerpts of this paper will be shown here, whenever obtained. There are other avenues to explore as well. The only thing formal, and unassailable, is a minimum compression value, while on the other hand, maximum compression limits are very much unknown. WD November 2004


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Pictures below are categorized in frames by sun elevation degrees. dV indicates vertical diameter and the number to the lower right indicates astronomical sun elevations(taken from a reliable astronomical program.

Dm131816 means
D: Differential refraction series; S means sunset series…
M: March 2002
13: Day 13
1816: 1816 UTC or GMT time.


2003 insert: New Generation pictures have also a new data section, which is horizontal diameter. These numbers can be found to the extreme lower left. The horizontal diameter is only calibrated by repititive process, the same camera took the same shot through identical telescopes and lenses. Horizontal refraction does exist, it may come as a surpriese to some, but the atmosphere is not at all homogenous, especially near the horizon. It would be very interesting if other webpages about differential refraction can be created at diverse locations so we can compare values. I encourage you, to do so. WD 2003.




OLD GENERATION


How it was done:

The digital pictures taken were done with equipment not quite "state of the art". A digital camera took photos right after a visual measurement was made with a monoscope.

Results are to be intercompared with the term "vdV", meaning visual vertical diameter, and "dV" vertical diameter by camera method. On the pictures at sun elevations above +2 degrees, it was noted that picture dimensions compared well with visual monoscope measurements. However at low elevations, below 2 degrees, digital camera pictures started to fail to match with visual results, this was caused by many reasons, namely: green and red flashes (no colour distinction captured), filter strength not appropriate with camera exposure settings and position of the camera with respect to the monoscope. At very low sun angles (+.5 to -1), no visual measurements were done due to the lack again of proper sun goggles and the unreadable monoscope scale due to a strong filter.

On several occasions verification of accuracy of the digital camera revealed no distortions provided a good exposure setting, but this was not always the case. The manual method literally can't measure a vertical compression when the sun was at high elevations and there was a few dozen arc seconds of compression, the scale was not refined enough, in this higher elevation case the photographic method
seemed to have worked flawlessly.

At elevations between -1 and +14 degrees, consideration must be given in comparing the manual measurement with the photographic one. At lower elevations between -1 and +2 degrees the manual method should be considered more accurate, with increasing elevations above 2 degrees the photographic method becomes more and more accurate. A few pictures show an important disagreement between visual and photographic results, they are caused by overexposing (the picture shows a blending of the corona with sun disk) and especially underexposing the camera settings at lower elevations, clouds and haze were noted to affect such readings as well.




NEW GENERATION PICTURES


As you might have noticed, the latest pictures have a higher resolution. They are dedicated to understand strong refraction mechanisms. Particular sun disk features, sunspots, and lunar craters are useful with this matter. The new pictures were taken from 2 different Telescopes, having sun specific filters. Most orange images are done with a Meade f=1250 mm Maksutov Cassegrain. Bright white sun disk images were done with a standard Celestron telescope.

Already some discoveries have been made, namely the confirmation that strong refraction causes large sunspot elevation gains. Low Moon shots are more difficult to understand, giving the fuziness at very low elevation shots. The Moon and sun shots can be differentiated by numbers placed above the moon image. They are total intensity (upper left) and angular size (upper right). There are no dV measurements done for the moon as well, just a vertical measurement using exactly the same scale from one picture to the next.



To see photos, click links on the menu