## Thursday, January 14, 2016

### HP 15C: Approximate Length of Sunlight During a Day

HP 15C:  Approximate Length of Sunlight During a Day

Source: Total Daily Amount of Solar Radiation - HP 67/97 Energy Conservation Pac, December 1978, Author: Hewlett Packard

Instructions:

Y Stack:  Enter the latitude (North as positive, South as negative).  Use the D.MMSS (degrees-minutes-seconds) format

X Stack:  The number of days after March 21.  A 365 day year is assumed, as well as assuming March 21 is the vernal equinox.

Run the program.

This is an approximation.

Program:

 Step Key Key Code 001 LBL E 42, 21, 5 002 DEG 43, 7 003 . 48 004 9 9 005 8 8 006 5 5 007 6 6 008 * 20 009 SIN 23 010 2 2 011 3 3 012 . 48 013 4 4 014 5 5 015 * 20 016 X<>Y 34 017 >H 43, 2 018 TAN 25 019 X<>Y 34 020 TAN 25 021 CHS 16 022 * 20 023 COS^-1  (ACOS) 43, 32 024 >RAD 42, 3 025 2 2 026 4 4 027 * 20 028 π 43, 26 029 ÷ 10 030 >H.MS 42, 2 031 RTN 43, 32

Example:

Los Angeles, April 17.  Latitude of 34°03’ N, 27 days after March 21.
Result:  approximately 12.5735 (12 hours, 57 minutes, 35 seconds)

Sydney, June 21.  Latitude of 33°51’31” S (enter as -33.5131), 92 days after March 21.
Result:  approximately 9.4439 (9 hours, 44 minutes, 39 seconds)

Rome, September 1.  Latitude of 41°51’ N, 164 days after March 21.
Result:  approximately 12.5323 (12 hours, 53 minutes, 23 seconds)

This blog is property of Edward Shore.  2016

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