ON Seasons and DayLight Saving Time____
On_Other_Stuff
This is presented as true to the best recollection and is offered
for guidance with NO warranty expressed or implied.
Your mileage may vary.
This tries to account for the Sun /vs/ Earth characteristics of each Season
and the singularities/boundaries in between, a.k.a. the Equinoxes and Solstices.
Corrections or additions appreciated.
Spring Equinox: approx March 21
Angle between a Sun's ray and the Earth's axis is 90deg.
Sun rises and sets directly East and West
Noon-day sun has Altitude as Alt=90-Lat.
North Pole: Sun follows around the horizon all day - clockwise
South Pole: Sun follows around the horizon all day - counterclockwise
Length of day and night are equal on the Equator.
Length of day and night are equal everywhere.
Lines of day-night are parallel to the meridians.
Spring-
Angle between a Sun's ray and the Earth's nothern axis decreases
from 90 to 67-deg.
Spot of Sunrise & Sunset moves North
Length of day and night are equal on the Equator.
No./So.Hemi: Days continue to get Longer/Shorter
No./So. Pole: Sun is always up/down
Summer Soltice: approx June 21
Angle between a Sun's ray and the Earth's northern axis is 67-deg.
Sun rises and sets furthest north: Azim=?__?
Noon-day sun has Altitude of ?__?
North Pole: Sun appears high all day long - clockwise
No. of Arctic Circle: Sun shines all day - clockwise
Length of day and night are equal on the Equator.
No./So.Hemi: Longest/Shortest day
No./So.Hemi: Days begin to get Shorter/Longer
Arctic Circle: Sun shines all day; dips to horizon at midnight
TropCan: Sun at noon has Altitude of 90deg.
Anarctic Circle: Sun seen only for a moment at high noon
So. of AnarcticCirc: Sun does not shine
South Pole: Sun does not appear all day long
Summer-
Angle between a Sun's ray and the Earth's nothern axis increases
from 67 to 90-deg.
Spot of Sunrise & Sunset moves South
Length of day and night are equal on the Equator.
No./So.Hemi: Days get Shorter/Longer
North Pole: Sun is up all day - clockwise
So. of AnarcticCirc: Days are rather short
South Pole: Sun is down all day
Autumnal Equinox: approx September 21
Angle between a Sun's ray and the Earth's axis is 90deg.
Sun rises and sets directly East and West
Noon-day sun has Altitude as Alt=90-Lat.
North Pole: Sun follows around the horizon all day - clockwise
South Pole: Sun follows around the horizon all day - counterclockwise
Length of day and night are equal on the Equator.
Length of day and night are equal everywhere.
Lines of day-night are parallel to the meridians.
Autumn-
Angle between a Sun's ray and the Earth's nothern axis increases
from 90 to 113-deg.
Spot of Sunrise & Sunset moves South
Length of day and night are equal on the Equator.
No./So.Hemi: Days continue to get Shorter/Longer
No./So. Pole: Sun is always down/up
Winter Soltice: approx December 21
Angle between a Sun's ray and the Earth's northern axis is 113-deg.
Sun rises and sets furthest south: Azim=?__? **
Noon-day sun has Altitude of ?__?
North Pole: Sun does not appear all day long
Length of day and night are equal on the Equator.
No./So.Hemi: Shortest/Longest day
No./So.Hemi: Days begin to get Longer/Shorter
No. of ArcticCirc: Sun does not shine
Arctic Circle: Sun seen only for a moment at high noon
TropCap: Sun at noon has Altitude of 90deg.
Anarctic Circle: Sun shines all day; dips to horizon at midnight
So. of Anarctic Circle: Sun shines all day - counterclockwise
South Pole: Sun appears high all day long - counterclockwise
Winter-
Angle between a Sun's ray and the Earth's nothern axis decreases
from 113 to 90-deg.
Spot of Sunrise & Sunset moves North
Length of day and night are equal on the Equator.
No./So.Hemi: Days get Longer/Shorter
South Pole: Sun is up all day - counterclockwise
No. of ArcticCirc: Days are rather short
North Pole: Sun is down all day
For Sun Rise/Set/Shine Tables and notes
see here.
==================
Daylight Saving Time is suppoed to make the most out of the daylight that we have
by shifting the wake up time for the majority to be closer to sunrise,
and hence not wasting it on their sleeping period.
By making the shift, there is more evening sun,
hence less artificial light is needed during their evening/refreshment time,
thus saving electricity, batteries, lamp oil, or candles.
Spring ahead; Fall Back:
In the Spring the clocks get set 1-hr ahead; 1-hr of sleep is lost.
Then the sun will rise and set 1-hr later than before;
i.e., less/more Sun in the Morn/Evening.
Essentially every time zone takes on the STD time of the next zone to the East.
If you forget, then you will be late for any appointment.
In the Fall the clocks get set 1-hr back; 1-hr of sleep is gained.
Then the sun will rise and set 1-hr earlier than before;
i.e., more/less Sun in the Morn/Evening.
Essentially every time zone takes on the DST time of the next zone to the West.
If you forget, then you will be early for any appointment.
If everybody just went by Greenwich Mean Time and adjusted their work/play hours
to suit their needs, then there would be NO need for the concept of DST,
but over the years we've become acustomed to having the Sun overhead at 12-Noon,
workday alarms set for about sunrise, and enough evening light for play.
===========================
Clocks and Power Failures ...
Definitions >
CC: Continuous-Clock: RealTimeOfDay/TOD, WindUp, BatteryPowered, SynchToRadio
DEC: Digital-Electric-Clock: Resets to 0 when power restored; NO BatteryBackup
EMC: Electro-Mechanical-Clock: Classic/Legacy/Original Electric Clock;
runs only when power is on
Before Power Failure::
CC = TOD
DEC= TOD
EMC= TOD
During a power Failure::
CC = TOD
DEC= n/a
EMC= F = Time OF Power Failure
Instant when power IS Restored::
CC = TOD when Power IS Restored
DEC= 0
EMC= F = Time OF Power Failure
After power is restored::
CC-DEC = R = Time OF power Restoration
CC-EMC = S = Span/Duration/Elapsed-time of power Outage
F = Time OF Power Failure
F = R-S = CC-DEC-(CC-EMC) =
EMC-DEC = F = Time OF Power Failure
===========================
Auto-Setting Clocks ...
Most need a manual setting for the correct Time-Zone;
some of these need a (Yes/No) setting for Daylight-Saving-Time/DST.
Some need a date setting to decide on DST;
some of these have fixed adhearnce to an UNchangeable calendar.
Most synch every-so-often with the Government Time Signal (e.g. WWV/WWVH);
where "every-so-often" is a variable.
some of these occasionally miss the DST flag/bit in the data stream.
Some synch only at the moment of being powered-up.