Re: Sundial Slang

[John Davis]

Hi John et al,   I couldn't let this pass without comment :-) !!   I'm not sure that I am in any position to "approve" the correct terms - the BSS Sundial Glossary is just a collection of the bits of information that I've pulled together from various sources, including much input from the participants of this list.  I have no problem with the use of slang terms, especially when they help those poor unfortunates that aren't sundial enthusiasts know what we're talking about.  It does need care, though, not to introduce or reinforce misapprehensions.  Most of John's terms seem to avoid this, though whether they are more easily understood than the "scientific" term is debatable.   One term which is common and not (yet) in the Glossary is "High noon".  Is this an americanism?  I have, of course, seen my cowboy movies, but am unclear where the term originates.  Is it that, with the relatively low latitudes in the south of America, the Sun can come close to directly overhead (altitude = 90 degrees) at noon?  If so, it reinforces the wrong view of much of the UK media that the Sun is at the "zenith" at noon.  Whilst many ordinary people think of "zenith" as the highest point of the arc, astronomically it is defined as the point which really is directly overhead (only expressed rather more formally!).   Another point to watch is the use of "due north" instead of celestial pole.  If you are at northerly latitudes, the difference between celestial and geographic north can be significant.  Why not use the Pole Star as a better everyday approximation?   "Horizon pollution" is an interesting term.  I guess we would define this as a percentage of the daylight period when the Sun falls on a particular site.  It's difficult to come up with a mathematical definition, as it depends on the Sun's declination as well as the positions of any obstructions.  Do we know of any dials at locations which can show the time over the full sunrise-sunset period thoughout the year?   Regards,   John ------------------------------------------------------ Dr J R Davis Flowton, UK 52.08N, 1.043E email: [EMAIL PROTECTED] ----- Original Message ----- From: John Carmichael To: sundial@rrz.uni-koeln.de Sent: 17 August 2001 16:07 Subject: Sundial Slang   Hi All, I've just finished the 7th edition of my Sundial Owner's Manual and realized that throughout the manual I explained sundial terms using sundial slang instead of the John Davis approved correct term. (Although at least in the Manual I place the correct term next to it in parenthisis) I also use sundial slang when I’m talking with others.  I feel a little guilty because I’m not using the correct terms.  But the slang serves a very useful purpose in that it is so intuitive and self-explanatory.  (The sundial purists are going to hate me for this!)   Anyway, here are a few of them… *High noon (Apparent Noon) Fuzz zone (The penumbra) Fuzz factor (formula that determines the width of the penumbra: F=1/100) The Correction graph (The Equation of Time) Sun height (solar altitude) Sun direction (solar azimuth) Due North (The Celestial Pole) Sun time (Apparent Time) Watch time (Standard Time) Date Ball (Spherical Nodus) Shadow caster (gnomon) The edge of the shadow caster (style) Moontime (time shown by moon shadows on a sundial) Time Zone correction (Longitudinal Shift) Horizon pollution (the objects around sundial that shade it from the sun.  ie. trees, buildings, mountains.  No correct term for this that I know of)  *As a sundial slang purist, I get upset, like any good dialist would, when my favorite radio station announces that it is High Noon (12:00 pm watch time), but because of our Time Zone Correction, it’s really only about 11:30 am Sun time! John   John L. Carmichael Jr. Sundial Sculptures 925 E. Foothills Dr. Tucson Arizona 85718 USA   Tel: 520-696-1709 Email: [EMAIL PROTECTED] Website: <http://www.sundialsculptures.com>