A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Byron Franklin
Date: 2011 Jul 11, 13:33 -0700
Byron; I know this is not exactly the subject, but This is how
I feel about the the idea of this man made, workable, system of
TIME and the need to be, as it is ,"simple."
OUR CLOCK TIME AND TIME ZONE.
By Byron Franklin QMCM Ret.
Our clock is an invention that controls our past present and future, with a steady uniform time. Two kinds of times are used in our daily living. We go about our day with little knowledge of these times and how they are used and why they are necessary. The most important time is SOLAR TIME that is the sun that apparently rotates around our home and the EARTH. Our clock at home on our shelf is based on he sun and regulates our life, to go to work, meet other people, come home, eat, and to get a good night sleep.
Our clock of today is accurate in measuring time, unlike the sun that has an apparent motion that some times off is off by many minutes.
Our local clock is a mean time having exactly equal division mechanically measuring our day and night.
We identify our local clock with where we live and the Longitude where we are located, we can call our CLOCK �LOCAL MEAN TIME� (LMT.)
It is best that the sun be high in the sky at our clock�s longitude when it reads 12:00 noon.
Another invention the second kind of time is TIME ZONES (TZ) it was needed to put the sun high in the sky at noon for all people and other locations on our earth; The Apparent movement of the sun around our earth is at 15 degrees in one hour (900 knots at our equator) so can not be high in the sky for all people on our round earth of 360 degrees.
TIME ZONES, GREENWICH ENGLAND was selected as the reference for the start of zero LONGITUDE and the ZERO TIME ZONE (TZ.)
The sun with it apparent speed of 15 degrees per hour would put the sun high in the sky at multiples of every 15 degrees around our earth. These 24 time zones starting at GREEWITCH ENGLAND. Enabled large zones of seven and one half degrees on each side of the prime, 15 degree center to keep the sun at 12:00 high in the sky on every one�s clock.
See TIME ZONE diagram.
Our TIME ZONE that our clock and LOCAL MEAN TIME depends on our LONGITUDE. And can be read off of the diagram. As ZONE DESCRIPTION (ZD) all we need is knowledge of our Longitude where we live. We can read ZD. As the action we must take to add or subtract the difference between 12:00 GMT and the GMT at our Longitude. At 75W we must add 5 hours to our LMT clock to get GMT.
GREENWITCH MEAN TIME
We are people of the world and must be able to plan and predict time not only at our TIME ZONE but at other TIME Zone�s. The TIME ZONE at 12:00 noon for the diagram is of GREENWITCH ENGLAND the other TIME Zone�s are later to the west and earlier to the east hemisphere, this means that the sun has already past to the east and LOCAL MEAN TIME is later will start it�s journey to the west where it is earlier.
The figure is designed to tell you what TIME ZONE description. You are in or belong to, and allows you to compute what local clock time is for the rest of the earth
Example: If your LONG were 5 degrees West than your ZONE TIME is at GREENWITCH. and 12:00 GREENWITCH MEAN TIME (GMT), your LOCAL MEAN TIME (LMT) would be also 12:00. For the rest of the earth GMT would also be 12:00 GMT. (There no time zones for GMT) in place we have TIME DESCRIPTION at each multiple of 15 degrees. TIME DESCRIPTION is the difference in time at GREEWITCH GMT and the time on the diagram for your LONGITUDE (LONG.)
If you were at LONG 72 west, your GMT would be 12:00 but the sun would be far from high in your sky. It will be five more hours
for the sun to be at your LONG.
So your ZONE DESCRITON is +5.
LOCAL MEAN TIME , your clock,
must be clock time - (minus) 5 hours
so your clock would read 07:00 LMT.
To find GMT again you would add
ZONE DESCRIPTION ZD
of + (plus) 5 hours to 07:00. If your
local clock reads 05:00 at 72 w than
GMT is 10:00 GMT.
RULES to CONVERT.
If you know LMT you must add the ZD.
To get GMT If you know GMT you
must reverse the sign and add ZD sign
and hours from GMT for LMT.using the
diagram, with any LONG. East or west
hemisphere you can find your ZD and�
GMT or LMT any where on our earth.
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