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  • #16
    Originally posted by Sunking View Post
    Just a note here. Magnetic South does not equal Solar South. You want Solar South. A one-hour time zone is 15 degrees.
    I'm not sure how the term solar south is defined, but if it means the time when the sun crosses the meridian of the site's local longitude, that is, when the azimuth angle of the sun at a location is 180 degrees, that time will vary for each day of the year and can be conceptualized or graphed as something called the analemma of the sun. It's that funny looking figure 8 you used to see on some globes. Also check out "analemma + Stanford Solar Center" on Google for some neat pictures and some text.

    One common term in use for that time is "solar noon".

    Relative to civil clock time (and leaving D.S.T. adjustments out of it for this discussion) which is partially based on based on each day being exactly 24 hours in length, and a non elliptical orbit, the variation in the time when solar noon occurs is mostly caused by the slightly elliptical nature of the earth's orbit, and to a lesser degree by the wobbling of the earth on its axis (like a top) called precession, and some gravitational effects from the moon and the sun.

    The magnitude of the annual variation of solar noon is about 30 minutes or so, from earliest to latest, with the variation being asymmetrical about civil clock mid day (noon) time and the degree of asymmetry f(longitude). The actual daily change is of the order of a few seconds/day.

    Example: yesterday (12/16/2017) at my location, solar noon was at 11:44:17 P.S.T. and some fraction of a second. Today it was at 11:44:45 P.S.T.and some fraction of a second.

    The earliest solar noon at my location occurs at 11:31:54 P.S.T. on 11/01 to 11/03.
    The latest solar noon at my location occurs at 12:02:37 P.S.T.on 01/10/ to 02/02.

    Those dates also wobble around by less than about 24 hours or so over a few years +/- some. .

    Consult the nautical almanac for details.

    All that and 5 bucks or more will get you a Starbucks.

    Last edited by J.P.M.; 12-17-2017, 04:25 PM.

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    • #17
      Originally posted by J.P.M. View Post
      One common term in use for that time is "solar noon".
      My bad and thanks for the correction. Solar South = Solar Noon down here. Where I live we point the panels straight up and level it. Pour a glass ow water on the panel, tap the south side of the panel with the bracket loosened up a bit, until the water just drains off, and tighten it down Perfect. No DST down here or anywhere south of TX has DST that I know of. In the USA daylight hours vary significantly from Summer to winter. Down here daylight hours do not vary much from Wet to Dry season. Err I should say Wet to Less Wet season. Almost exactly 1 hour difference. Shortest day of the year is 11 hours and 36 minutes, longest day is 12 hours and 39 minutes.

      Being a Weatherman is an easy job here. Forecast for every day is low in the mid 50's, highs in the mid 80's with a chance of rain. It is spring everyday Panama City is even easier to forecast Hot and humid with a chance of rain. About the only thing that changes is humidity. Wet season is sticky, and dry season is less sticky and humid.

      Remember when 25 cents would by a cup of coffee and a conversation at any dinner? That still exist down here and we have the best coffee in the world.
      Last edited by Sunking; 12-17-2017, 08:29 PM.
      MSEE, PE

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      • #18
        Originally posted by Sunking View Post

        My bad and thanks for the correction. Solar South = Solar Noon down here. Where I live we point the panels straight up and level it. Pour a glass ow water on the panel, tap the south side of the panel with the bracket loosened up a bit, until the water just drains off, and tighten it down Perfect. No DST down here or anywhere south of TX has DST that I know of. In the USA daylight hours vary significantly from Summer to winter. Down here daylight hours do not vary much from Wet to Dry season. Err I should say Wet to Less Wet season. Almost exactly 1 hour difference. Shortest day of the year is 11 hours and 36 minutes, longest day is 12 hours and 39 minutes.

        Being a Weatherman is an easy job here. Forecast for every day is low in the mid 50's, highs in the mid 80's with a chance of rain. It is spring everyday Panama City is even easier to forecast Hot and humid with a chance of rain. About the only thing that changes is humidity. Wet season is sticky, and dry season is less sticky and humid.

        Remember when 25 cents would by a cup of coffee and a conversation at any dinner? That still exist down here and we have the best coffee in the world.
        RUA ! (Read, Understood, Acknowledged). No correction, just clarification. I learn more terms every day. Never knew coke meant any flavor of soda until I spent some time in AL w/in-laws. DST doesn't usually enter into the geometric calcs/solar position algorithms until the end, if at all.

        Around San Diego, being a weatherman means being able to say "cloudy early, then sun".

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        • #19
          Originally posted by J.P.M. View Post
          Around San Diego, being a weatherman means being able to say "cloudy early, then sun".
          I hear you. Wished I had known you lived in SD back in 2016. I was there late March 2016. We stayed in a area you might know of or about where it is. We stayed at a old friend of mine house from the Navy that works for Northrop Grumman in El Cajon. It is on a hill and was an old Stage Couch Station. Just off the intersection of Washington and Anza. Fantastic view of the city. He owns most of the property on top of the hill. The the old Stage Couch Station is still there and historically protected.

          MSEE, PE

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          • #20
            Originally posted by Sunking View Post
            I hear you. Wished I had known you lived in SD back in 2016. I was there late March 2016. We stayed in a area you might know of or about where it is. We stayed at a old friend of mine house from the Navy that works for Northrop Grumman in El Cajon. It is on a hill and was an old Stage Couch Station. Just off the intersection of Washington and Anza. Fantastic view of the city. He owns most of the property on top of the hill. The the old Stage Couch Station is still there and historically protected.
            a hill ~~ 3/8 of a mile ESE of the intersection ? Got some structures on top of it ? Lots of single lane roads ?

            Know where it is but don't get there much. Looks like kind of an eclectic neighborhood.

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