New York DAYLIGHT explanation

Civil twilight is defined to begin in the morning, and to end in the evening when the center of the Sun is geometrically 6 degrees below the horizon. This is the limit at which twilight illumination is sufficient, under good weather conditions, for terrestrial objects to be clearly distinguished; at the beginning of morning civil twilight, or end of evening civil twilight, the horizon is clearly defined and the brightest stars are visible under good atmospheric conditions in the absence of moonlight or other illumination. In the morning before the beginning of civil twilight and in the evening after the end of civil twilight, artificial illumination is normally required to carry on ordinary outdoor activities. Complete darkness, however, ends sometime prior to the beginning of morning civil twilight and begins sometime after the end of evening civil twilight. START OF CIVIL TWILIGHTDec 7 2006-6:35AMDec22 2006-6:46AMJan 6 2007-6:49AM

CP-runner wrote:

I might be missing something simple, basics earth/sun movements but can someone please explain how daylight works...

If Dec 22nd is the longest night, and if you go back 15 days (from dec 22) and forward 15 days (from dec 22), then why is the light in the morning at 6:45am not the same?

The problem is that 15 days before Dec 22nd, I was able to go to Central Park and run at 6:45am, but 15 days after Dec 22nd, I was not able to go at 6:45am because it was too dark, and it did not gt lighter until 7am.

The imple answer would be to go running later bt I can't because I need to finis the run and get to work.

I would love to get he physical explanation for this, I'm very curious.

I'll leave it to the learned ones to do the orbital tragectories of sol but I'll reinforced your contention that it was darker on 6 Jan at 6:45AM (4 minutes UNTIL civil twilight) than on 7 Dec at6:45AM (10 minutes AFTER civil twilight).

We need Mr. Wizard, a working lightbulb, a ping-pong ball and a grapefruit marked with lines of latitude and longitude. Mr Herbert will mark an x on the grapefruit for our position on the earth The ask little Sally to walk around ......................

Good question CP-runner. Been some, um, good & let's-just-call'em-bad answers to your query.

While we're busy solving riddles about the universe, can somebody explain for me why enormous numbers of people will pay good money to walk & run indoors (treadmills & indoor tracks) during daylight hours between Apr 1-Oct 31 in the northern hemisphere? Thanks in advance.

scotth wrote:

Good question CP-runner. Been some, um, good & let's-just-call'em-bad answers to your query.

While we're busy solving riddles about the universe, can somebody explain for me why enormous numbers of people will pay good money to walk & run indoors (treadmills & indoor tracks) during daylight hours between Apr 1-Oct 31 in the northern hemisphere? Thanks in advance.

Scott, I will go ahead and award you with the post of the week. Thanks for the laugh....

wineturtle, you're late to the party.

wineturtle wrote:

Civil twilight is defined to begin in the morning, and to end in the evening when the center of the Sun is geometrically 6 degrees below the horizon. This is the limit at which twilight illumination is sufficient, under good weather conditions, for terrestrial objects to be clearly distinguished; at the beginning of morning civil twilight, or end of evening civil twilight, the horizon is clearly defined and the brightest stars are visible under good atmospheric conditions in the absence of moonlight or other illumination. In the morning before the beginning of civil twilight and in the evening after the end of civil twilight, artificial illumination is normally required to carry on ordinary outdoor activities. Complete darkness, however, ends sometime prior to the beginning of morning civil twilight and begins sometime after the end of evening civil twilight.

START OF CIVIL TWILIGHT

Dec 7 2006-6:35AM

Dec22 2006-6:46AM

Jan 6 2007-6:49AM

A little bit of plagiarism here?

Levin Memorial Hillrunner wrote:

Civil sunset and rise in NYC are a bit different because rise is from east with LI and ocean, little pollution while set goes into the smoggy inversion layer over NJ and effects the suns ability to "curve" around the horizon. IE nothig to deflect the rising rays and a whole lot of sh!t working to mask the setting rays.

More:

http://aa.usno.navy.mil/faq/docs/RST_defs.html

You are correct I neglected to post the link from this post(mine BTW)

where I found the info- please don't take my posting card away!!Posting under a comic name can bite your ass if the board police catch you.

So many factors...

- people like spending money

- people don't know where to spend their money

- it can be amazingly cold outdoors regardless of time of day

- easier running

- requires less focus, the treadmill makes you move

- less distractions, not as many attractive women in gyms than there are outdoors (my personal though)

- You don't need to deal with the extreme cold and hot weather when you are indoors, you know exactly what you need to wear

- ipods remain cleaner

I like distractions though, let's see how long I can keep running outdoors this year, it's getting cold.

outdoors runner wrote:

I like distractions though, let's see how long I can keep running outdoors this year, it's getting cold.

Please spare us; first it's the dark, now it's the cold, I suppose next you're going to say the rain is keeping you from running?

Wejo, please return this lost thread back to Runner's World where it belongs.

Word

malmo wrote:

[quote]outdoors runner wrote:

Please spare us; first it's the dark, now it's the cold, I suppose next you're going to say the rain is keeping you from running?

Wejo, please return this lost thread back to Runner's World where it belongs.

malmo, how dare you trivialize a considered answer to MY question!!

Bless you.