Talk:Solar irradiance

There are numerous major misconceptions and miss-statements in this article. It needs thorough reworking by experts knowledgeable in solar science. See NASA SORCE at http://lasp.colorado.edu/home/sorce/ etc.DLH (talk) 18:15, 1 January 2015 (UTC)[reply]

Recently this edit by Lfstevens, removed what appears highly cited papers. However the entire manual references belong inline with the content. Thus, i suggest to remove all manual references, and if possible move them to the correct content. Maybe the editor can explain why remove only a few paper studies. prokaryotes (talk) 04:46, 15 August 2015 (UTC)[reply]

See What is the difference between insolation and solar irradiance? http://www.researchgate.net/post/What_is_the_difference_between_insolation_and_solar_irradiance prokaryotes (talk) 19:00, 15 August 2015 (UTC)[reply]

I have no opinion about the answer, but perhaps we should look for something more authoritative? Lfstevens (talk) 07:04, 16 August 2015 (UTC)[reply]

This looks like a more credible source: http://www.volker-quaschning.de/articles/fundamentals1/index.php The distinction they make is "The total specific radiant power, or radiant flux, per area that reaches a Spectrum AM 0 (extraterrestrial) Spectrum AM 1.5 (terrestrial) receiver surface is called irradiance. Irradiance is measured in W/m² and has the symbol E. When integrating the irradiance over a certain time period it becomes solar irradiation. Irradiation is measured in either J/m² or Wh/m², and represented by the symbol H", so I think Irradiance is power per area, "solar irradiation" or insolation is energy per area. Chthonicdaemon (talk) 05:57, 28 September 2015 (UTC)[reply]

Yes, Solar Irradiance and Insolation (Solar Irradiation) are often confused and their meanings and units are conflated in this article. The name of the article needs to be changed to include both ("Solar Irradiance and Irradiation" perhaps), or there should be two articles, one on Solar Irradiance and the other on Solar Irradiation (which is now the preferred way to refer to Insolation). Having them both in the same article might make sense because Irradiation is simply the integral of Irradiance over a given time interval. Indeed the www.volker-quaschning.de source cited here is more credible than the www.researchgate.net source. JDHeinzmann (talk) 11:38, 30 October 2015 (UTC)[reply]

I would be strongly in favour of a separate article on insolation, which can depend on altitude, latitude, cloud cover, wavelength (UV insolation is considerably weaker than IR insolation), nearby reflectors, etc.

Solar irradiance on the other hand is independent of all of those variables except wavelength, with "total" often meaning "over all wavelengths". Nominally it is the irradiance at top of atmosphere, but since both the solar luminosity and distance of Earth from the Sun varies from day to day, different authors implicitly take it to be the mean over one or both of these factors, averaged over a specified period. For example the several articles in Haigh et al's book "The Sun, Solar Analogs and the Climate" use "solar iradiance", "total solar irradiance", and "bolometric irradiance" without definition making it unclear how they differ.

A definition of solar irradiance I'd be fine with is the irradiance from the Sun at a distance of 1 AU from the Sun. (This definition is kept simple by modeling the Sun as a spherically symmetric radiator.) Equivalently solar irradiance is the quotient of solar luminosity by the area of a sphere of radius 1 AU cocentric with the Sun. These are to be understood as instantaneous notions; one can then speak of mean solar luminosity, and hence mean solar irradiance, averaged over a specified period of time. (The article Solar luminosity complicates the notion with a factor of k apparently on the assumption that the notion is defined as the annual mean where distance varies according to Kepler's Second Law while luminosity is either constant or an annual average.)

My understanding of "total" in TSI, based on usage, is as a spectral notion, namely "integrated over all wavelengths"; thus one can say "UV solar irradiance" but not "UV total solar irradiance". Logically "total solar luminosity" would therefore also be a spectral notion, but instead "total" in that context is more often used redundantly to emphasize that luminosity is irradiance integrated over area.

Meanwhile there are some egregious errors in this article, such as mixing up energy and power, but I would nevertheless suggest fixing the definitions before fixing the errors since the latter depend on the former. Vaughan Pratt (talk) 17:06, 13 December 2015 (UTC)[reply]

While I can glean/infer the meanings of these terms from the discussion, I'd instead suggest that we refer to an authoritative source and go with that. Can anyone provide one? Lfstevens (talk) 07:43, 14 December 2015 (UTC)[reply]

The first sentence of the article says "Solar irradiance (also Insolation, from Latin insolare, to expose to the sun)[1][2] is the power per unit area produced by the Sun in the form of electromagnetic radiation" but the units stated further along are MJ/m². There are also many ambiguous units like kWh/m²/day and such. I think the units should all be power/area as in the definition. Chthonicdaemon (talk) 04:30, 28 September 2015 (UTC)[reply]