Wikipedia:Reference desk/Archives/Miscellaneous/2017 February 3

= February 3 =

Daylight intensity by month?
So here in the centre of the UK (yes centre, not center!) I'm sure the days seem brighter than say, 21st of December. What I'm curious to know, however is how the peak lightness of the day varies between month to month or better still day to day? IE How much brightness do we gain per day etc etc. Is there somewhere with the relevent info to find out? — Preceding unsigned comment added by 74.215.182.131 (talk) 13:43, 3 February 2017 (UTC)


 * This page contains a utility to calculate your solar irradiance by location, date, and direction you are facing. -- Jayron 32 14:08, 3 February 2017 (UTC)


 * However, 74.215 asked about the peak intensity (which depends only the sun's highest altitude above the horizon); that page gives the total irradiance during the day, which also depends on the length of time the sun is up.


 * It should be trigonometrically obvious that, if we ignore the weather and the eccentricity of the Earth's orbit, then the intensity of sunlight reaching the ground at any particular time is proportional to the sine of the sun's angle of elevation (how high it is above the horizon). And that if you're in the co-called temperate zones, then at noon local solar time on the summer solstice the sun reaches its highest-ever angle of elevation, equal to the complement of your latitude (90° minus your latitude) plus the Earth's axial tilt of about 23.5&deg;, whereas at noon local solar time on the winter solstice then it's the complement of your latitude minus the axial tilt.  So consider for example latitude 51.5° (e.g. London, England).  The complement of that is 38.5°, so the peak altitude of the sun in the day varies from 15° to 62°; therefore the minimum peak lightness of the day would be sin 15° / sin 62° or a bit over 29% of the maximum.  On the other hand, in, say, Orlando, at latitude 28.5°, the calculation would be sin 38° / sin 85°, so the minimum is almost 62% of the maximum.


 * But I said this was ignoring the eccentricity of the Earth's orbit. The Earth about 3.4% nearer the Sun at perihelion than at aphelion.  And since light follows an inverse square law, this means that the intensity of sunlight when the sun is at the same angle of elevation is about 6.9% greater at perihelion than at aphelion.  Since the date of perihelion happens to the close to the winter solstice in the Northern Hemisphere, this acts against the effect of the angle of elevation and means that in London the minimum peak lightness would be more like 31% of the maximum, rather than 29%.


 * Hope this helps. --76.71.6.254 (talk) 07:47, 4 February 2017 (UTC)

Raphael
What was Raphael's opinion on Transubstantiation? Thanks, --76.85.197.191 (talk) 16:29, 3 February 2017 (UTC)
 * Assuming you mean Raphael the painter, he did paint Disputation of the Holy Sacrament which may give some insight as to his recognition of the debates around the Eucharist. As to his personal opinion, I cannot find any information one way or the other, but he was an active Roman Catholic and was not apostate, so one may presume he held the official church position, but that would only be an assumption, as I can't find any statement from him on the matter.  -- Jayron 32 17:56, 3 February 2017 (UTC)
 * I will buy a coffee, beer, or donut for ANYONE who can supply a reference to the opinion of Raphael (ninja turtle), regarding transubstantiation. SemanticMantis (talk) 18:59, 3 February 2017 (UTC)
 * Wouldn't it be more appropriate to buy a pizza? --47.138.163.230 (talk) 01:30, 4 February 2017 (UTC)
 * The original Raphael was an archangel, so presumably he knows the truth about transubstantiation. When you know the truth, you don't need an opinion. Wymspen (talk) 20:18, 3 February 2017 (UTC)
 * Not according to the buzz from the USA leadership about the relative value of truth [= facts] vs. opinion... -- Deborahjay (talk) 10:19, 4 February 2017 (UTC)
 * The US doesn't have leadership, it has a president and elected representatives, and a federal judiciary. See Fuehrer. μηδείς (talk) 02:49, 5 February 2017 (UTC)