Willim's Page 252

252 The Philippine Islands, P.I., π Are In The Tropics

For part of the year from Autumnal Equinox to Vernal Equinox, including "The Northern Winter," the Sun is South of the Equator. For the rest of the year from Vernal Equinox  to Autumnal Equinox, including "The Northern Summer," it is North of the Equator. During the hottest times of the year the Sun will be shining on the Northern faces of buildings in the Philippines and other places North of the Equator but South of the Tropic of Cancer. North of the Tropic of Cancer, 23.5^N, the Sun will only shine on the Southern faces of the buildings.

The Earth does not go around the Sun at a constant rate so I used the dates of the equinoxes and solstices and then assumed constant a constant rate between them. The [dates] in the square brackets are taken from Greenwich Mean Time web site and show the actual dates and time of the occurrences.

The days of the equinoxes and solstices for other years can be obtained from:- http://wwp.greenwichmeantime.com/longest-day/index.htm

The table below shows the approximate dates the Sun reaches various latitudes. It can be seen from the table that in Cebu at 10^ North, the Sun will be North of Cebu from 15-April to 26-August for most years.

Other areas of the Philippines can be estimated from the South of Mindanao is approx 5^N and North of Luzon is approx 15^N. The exact latitudes of locations in the Philippines or elsewhere on Earth can be obtained from Bing Maps, Google Maps, NOAA or Google Earth etc.

The Tropics of Capricorn and Cancer were at 23.43721^ (23^ 26' 13.9") North & South as of January 2016.

# Summer Solstice [20-Jun-2016 22:34] 23.43721^N
23^N 09-Jun-2016 12:39 . . . . . 02-Jul-2016 11:08
20^N 19-May-2016 13:26 . . . . . 22-Jul-2016 15:17
15^N 30-Apr-2016 04:45 . . . . . 11-Aug-2016 04:29
10^N 15-Apr-2016 05:12 . . . . . 26-Aug-2016 07:32
05^N 01-Apr-2016 21:10 . . . . . 09-Sep-2016 18:41

0^. [20-Mar-2016 04:30] . . . . [22-Sep-2016 14:21]
. . Vernal Equinox . . . . . . . Autumnal Equinox
0^. [20-Mar-2017 10:08]

05^S 07-Mar-2017 05:53 . . . . . 05-Oct-2016 21:29
10^S 22-Feb-2017 10:51 . . . . . 18-Oct-2016 19:30
15^S 07-Feb-2017 01:59 . . . . . 02-Nov-2016 07:48
20^S 20-Jan-2017 12:12 . . . . . 21-Nov-2016 01:53
23^S 31-Dec-2016 09:28 . . . . . 10-Dec-2016 09:25
# Winter Solstice [21-Dec-2016 10:45] 23.43721^S

For better estimates set your location and time zone in this spreadsheet.

 Link to Solar_Position_W_01.ods [41kb] approx. ODS Calc icon

The dates in the above table can be used as guidance for one's "starting" dates.

The objective is to get the Sun Altitude/Elevation as close to 90^ as possible by experiment to determine which days solar noon Sun Azimuth/Direction changes from 180 to 0/360 or vice versa.

Alternatively visit the NOAA Online Sun Azimuth Elevation Calculator

https://www.esrl.noaa.gov/gmd/grad/solcalc/azel.html

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