Monday 11 December 2017

Sundial mean solar time

LOCAL CORRDINATES: Latitude 45⁰ 43’ 30” Longitude 9⁰ 30’ 56”
DECLINATION OF SOUTH-EAST WALL: 2⁰
ORTOSTILLO: 22 CM

The time we read on our wrist watches is known as local time or (in Italy) Central European Time (CET).
Twelve noon local solar time (LST) is defined as when the sun is at its highest in the sky.
The local time can be calculated from reading the clock and applying the following formula:


TMEC=TV+a+b+c

a: local constant
Time due to the difference in longitude between the location and the local standard time meridian. For central Europe the local standard time meridian (LSTM) lies at 15⁰ longitude East.

Each degree of longitude corresponds to 4 minutes.
The sign is positive if the location is West of the LSTM and negative if it lies East of the LSTM.
AT THIS LOCATION THE LOCAL CONSTANT IS EQUAL TO +21 MINUTES AND 56 SECONDS.

b: time equation in minutes.
The sign is positive from the 13/06 to 1/9 and from 25/12 to 15/04, whilst the sign is negative from 15/4 to 13/06 and from 1/09 to 25/12.

The value of the time equation is stated in the table below.

c: add one hour when daylight saving time (DST) applies..



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