#!/usr/bin/perl
use warnings;
use strict;
use 5.010;

use Astro::Utils;
use DateTime;
use DateTime::Event::Sunrise;
use DateTime::Format::Strptime;
use DateTime::Format::Human::Duration;

my $LONG = -122.5;                  # E = +, W = -
my $LAT  = 45;                      # N = +, S = -
my $ZONE = 'America/Los_Angeles';

for my $sun_height ( 0, -0.833, -6, -12, -18 ) {

   my $sun = DateTime::Event::Sunrise->new(
      precise   => 1,
      longitude => $LONG,
      latitude  => $LAT,
      altitude  => $sun_height
   );
   say "sun height is $sun_height";
   my $strp = DateTime::Format::Strptime->new(
      pattern   => '%Y-%m-%d %H:%M:%S',
      time_zone => 'UTC',
      on_error  => 'croak'
   );
   my $durfmt = DateTime::Format::Human::Duration->new();

   print "At "
     . abs($LAT)
     . ( $LAT > 0 ? "N" : "S" ) . " "
     . abs($LONG)
     . ( $LONG > 0 ? "E" : "W" ) . ":\n";
   my $now_year = DateTime->now->year;
   for my $year ($now_year) {
      print " In $year:\n";
      my @seas = (
         [
            'Spring', 'March equinox', calculate_equinox( 'mar', 'utc', $year )
         ],
         [
            'Summer',
            'June solstice',
            calculate_solstice( 'jun', 'utc', $year )
         ],
         [
            'Fall',
            'September equinox',
            calculate_equinox( 'sep', 'utc', $year )
         ],
         [
            'Winter',
            'December solstice',
            calculate_solstice( 'dec', 'utc', $year )
         ],
      );
      for my $seas (@seas) {
         my ( $sname, $when, $start ) = @$seas;
         $start = $strp->parse_datetime($start);
         $start->set_time_zone($ZONE);
         my $rise = $sun->sunrise_datetime($start);
         my $set  = $sun->sunset_datetime($start);
         my $dur  = $durfmt->format_duration_between( $rise, $set );
         print "  $sname begins on the $when at ",
           $start->strftime('%Y-%m-%d %H:%M:%S %Z'), ".\n";
         print "   Sunrise is at ", $rise->strftime('%H:%M:%S %Z'),
           ", sunset is at ", $set->strftime('%H:%M:%S %Z'), ",\n";
         print "   and the day is $dur long.\n";
      }
   }

}

##</code><code>##

C:\Users\Fred\Desktop>perl astro5.pl
sun height is 0
At 45N 122.5W:
 In 2016:
  Spring begins on the March equinox at 2016-03-19 21:29:48 PDT.
   Sunrise is at 07:15:36 PDT, sunset is at 19:17:02 PDT,
   and the day is 12 hours, 1 minute, and 26 seconds long.
  Summer begins on the June solstice at 2016-06-20 15:33:55 PDT.
   Sunrise is at 05:27:45 PDT, sunset is at 20:53:24 PDT,
   and the day is 15 hours, 25 minutes, and 39 seconds long.
  Fall begins on the September equinox at 2016-09-22 07:20:41 PDT.
   Sunrise is at 07:02:13 PDT, sunset is at 18:58:39 PDT,
   and the day is 11 hours, 56 minutes, and 26 seconds long.
  Winter begins on the December solstice at 2016-12-21 02:44:00 PST.
   Sunrise is at 07:50:12 PST, sunset is at 16:24:55 PST,
   and the day is 8 hours, 34 minutes, and 43 seconds long.
sun height is -0.833
At 45N 122.5W:
 In 2016:
  Spring begins on the March equinox at 2016-03-19 21:29:48 PDT.
   Sunrise is at 07:10:53 PDT, sunset is at 19:21:45 PDT,
   and the day is 12 hours, 10 minutes, and 52 seconds long.
  Summer begins on the June solstice at 2016-06-20 15:33:55 PDT.
   Sunrise is at 05:22:01 PDT, sunset is at 20:59:08 PDT,
   and the day is 15 hours, 37 minutes, and 7 seconds long.
  Fall begins on the September equinox at 2016-09-22 07:20:41 PDT.
   Sunrise is at 06:57:30 PDT, sunset is at 19:03:21 PDT,
   and the day is 12 hours, 5 minutes, and 51 seconds long.
  Winter begins on the December solstice at 2016-12-21 02:44:00 PST.
   Sunrise is at 07:44:32 PST, sunset is at 16:30:35 PST,
   and the day is 8 hours, 46 minutes, and 3 seconds long.
sun height is -6
At 45N 122.5W:
 In 2016:
  Spring begins on the March equinox at 2016-03-19 21:29:48 PDT.
   Sunrise is at 06:41:38 PDT, sunset is at 19:51:05 PDT,
   and the day is 13 hours, 9 minutes, and 27 seconds long.
  Summer begins on the June solstice at 2016-06-20 15:33:55 PDT.
   Sunrise is at 04:44:34 PDT, sunset is at 21:36:35 PDT,
   and the day is 16 hours, 52 minutes, and 1 second long.
  Fall begins on the September equinox at 2016-09-22 07:20:41 PDT.
   Sunrise is at 06:28:12 PDT, sunset is at 19:32:35 PDT,
   and the day is 13 hours, 4 minutes, and 23 seconds long.
  Winter begins on the December solstice at 2016-12-21 02:44:00 PST.
   Sunrise is at 07:10:39 PST, sunset is at 17:04:27 PST,
   and the day is 9 hours, 53 minutes, and 48 seconds long.
sun height is -12
At 45N 122.5W:
 In 2016:
  Spring begins on the March equinox at 2016-03-19 21:29:48 PDT.
   Sunrise is at 06:07:16 PDT, sunset is at 20:25:33 PDT,
   and the day is 14 hours, 18 minutes, and 17 seconds long.
  Summer begins on the June solstice at 2016-06-20 15:33:55 PDT.
   Sunrise is at 03:54:46 PDT, sunset is at 22:26:23 PDT,
   and the day is 18 hours, 31 minutes, and 37 seconds long.
  Fall begins on the September equinox at 2016-09-22 07:20:41 PDT.
   Sunrise is at 05:53:49 PDT, sunset is at 20:06:52 PDT,
   and the day is 14 hours, 13 minutes, and 3 seconds long.
  Winter begins on the December solstice at 2016-12-21 02:44:00 PST.
   Sunrise is at 06:33:22 PST, sunset is at 17:41:44 PST,
   and the day is 11 hours, 8 minutes, and 22 seconds long.
sun height is -18
At 45N 122.5W:
 In 2016:
  Spring begins on the March equinox at 2016-03-19 21:29:48 PDT.
   Sunrise is at 05:32:02 PDT, sunset is at 21:00:56 PDT,
   and the day is 15 hours, 28 minutes, and 54 seconds long.
  Summer begins on the June solstice at 2016-06-20 15:33:55 PDT.
   Sunrise is at 02:48:34 PDT, sunset is at 23:32:32 PDT,
   and the day is 20 hours, 43 minutes, and 58 seconds long.
  Fall begins on the September equinox at 2016-09-22 07:20:41 PDT.
   Sunrise is at 05:18:36 PDT, sunset is at 20:41:56 PDT,
   and the day is 15 hours, 23 minutes, and 20 seconds long.
  Winter begins on the December solstice at 2016-12-21 02:44:00 PST.
   Sunrise is at 05:57:35 PST, sunset is at 18:17:31 PST,
   and the day is 12 hours, 19 minutes, and 56 seconds long.