New York DAYLIGHT explanation

The thing is, although the solstice is the shortest day of the year, it is not the day that the sun rises the latest. Your days are getting longer in the evenings, not the mornings.

I am not qualified to give a scientific explanation of this, but that's the physical reality of what's going on.

Here's some info about sun rise/set:

http://www.wunderground.com/about/faq/twilights.asp

The shortest day is 21st or 22nd December but due to angle of earth's axis/rotation etc this is different from the latest sunrise and earliest sunset. These are on different days so it starts staying light longer each evening for a period while it is still staying dark for longer each morning.

If i recall, here in London the earlist sunset was around 7 December but latest sunrise was early January.

I may have that the wrong way round but hopefully you get the point.

Doh, took too long typing...

It has to do with the orbit of the Earth, and it's postion of the Earth's axis. To make things really easy, divide the calendar into quarters. In December and June you have the winter and summer solstice, when you have the shortest and longest days. Then, in the spring and fall, you have daylight savings and the return to standard times.

Even though the duration of "night" was it's longest at the winter solstice, most consider it the shortest day. So what was happening is that the days have been getting shorter up until the 22nd, and then they start to increase in duration again. But, the time that the day starts is pushed back, as you've noticed. this has to do with the Earth's axis in relationship to the postion of the sun.

Starting January 15, sunrise will begin earlier. On December 7, civil twilight began at 6:35a, at 6:46a on Decmber 22, and at 6:49a on January 5th. On February 3, civil twilight will again begin at 6:35a.

The real question is why you have to wait till it's light to go running. There are hundreds of runners in the park from 5 a.m. on.

Maybe they want to be able to see the ground a little better. Maybe they still don't feel safe even with "hundreds of runners". Maybe they just plain don't like running in the dark.

The real question is why you can't understand that not everyone thinks like you.

Voice of reason, I've been running in CP for many many years and there really aren't "hundreds of people running starting at 5am". Even NY is not that crazy. :) It is not safe to run in CP (or most public locations, for that matter) when it is dark, or before day break, you can not see clearly which makes these locations dangerous. To say the least, perhaps more so for women than it is for men.

I would like to request that no one turns this into "women being afraid to go out", "if only you were brave enough" etc etc... That is not the intention of this thread nor the point. The one and only and "real" point of this thread is simply a question about seasons & the solar system.

Thank you all for your answers, I need to think about them a little more to really understtand it but I think it's making sense. Not to sound cheesy, but nature is amazing. :) As you can tell, I had a nice run this morning and am happy.

Just wanted to add a little data to the conversation. Please note the below are approximations.

Let's assume there are hundreds of people in Central Park at ~6am, say 300

The longest (single) loop in the Park is ~6miles which means:

~ 50 runners per mile

~ 100 ft between 2 runners (300/6miles & convert to ft)

Or ~35meters between 2 runners

100ft is actually quite a bit of a distance, when you think about it. At 6am in the morning.

What if its cloudy? Do wait an extra 10 min?

People run in the dark at CP all the time. Being able to still get in a good run when is dark is the only real benefit of running in NYC. As long as their are a good number people out its safe.

Anyway CP is for yuppy penguins and I am glad I don't run there no more.

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.

If the Earth's rotation about the sun was circular then the sunrise on the 'shortest' day (solstice) would be the latest and the sunset the earliest. On each successive day after the solstice, both sunrise and sunset would change at the same daily rate. Centered between the two is solar noon, which would remain the same.

Since the Earth has an elliptical orbit around the Sun, solar noon changes during the year, meandering within 10 minutes or so from either side of nominal noon. It just happens that solar noon had moved enough from Dec 22 to Jan 01 (11:54 to 12:03 = 9 minutes) to offset the minutes gained in daylight (1/2 of 14 minutes) so that the net result was that Sunrise on Jan 10 came 2 minutes later than on Dec 22. Solar noon will continue to drift positive until about Feb 10 (12:10) before turning back towards negative again, but that will have little effect on sunrise/sunset because the daylight hours are accelerating faster than the change in solar noon.

Back to the original question. Sunrise was only 2 minutes later yet you perceived it was "too dark to run" on Jan 10 yet OK to run on Dec 22? Without doing any other research I'd suggest it was one of two things, cloud cover or (lack of) moonlight. Both make a big difference on those twilight runs.

I'm with the other guy, you said, "too dark to run?" I almost fell off of my chair laughing. Unless you have a specified problem with night vision, your eyes are engineered so that they dilate in the dark, plus the park has streetlights everywhere. Don't be afraid of the dark, I've probably run over 40,000 miles in the dark, and the boogeyman never got me once!

What is it with those living in Brooklyn calling CP for "yuppy penguins", come on runners, you happen to live in Broolyn so you run in Prospect Park, those that live near CP in Manhattan, run there, why does it have to become a class issue...

I'm sure you wouldn't mind if prospect park had a 6miles loop, it's really what you make out of it. Don't let the yuppies or whatever else you don't like bother your run.

Maria Isabel Monteiro Alves was killed jogging in the Park in 1995 and since then I've stopped running in the Park solo in the dark. I don't mind you laughing at me or rolling your eyes. I'm still alive. I run other places in the dark where I feel comfortable. Central Park and the accompanying woods especially in the Northern section is not one of those places.

1995? What does that mean? Besides the fact that it was a tragic, random incident.

If there is a car accident on a nearby expressway with a fatality, do you stop driving on that road forever?

malmo wrote:

I've probably run over 40,000 miles in the dark, and the boogeyman never got me once!

Maybe YOU are the boogeyman!

here's all you need to know:

http://www.timeanddate.com/worldclock/astronomy.html?n=179&month=1&year=2007&obj=sun&afl=-11&day=1

in case that was too hard to manipulate, here's Dec 2006

http://www.timeanddate.com/worldclock/astronomy.html?n=179&month=12&year=2006&obj=sun&afl=-11&day=1

Malmo, it only takes one event. It's clear that the hundreds of people do not create safety in CP or any other public place when it is dark. Beating, rape do not happen often, but they are a concern.

This doesn't mean that people are scared but that they can find alternative locations for running when needed. 5th Ave or CPW are just as good for dark mornings, very little traffic, you still see other runners and enjoy the City.

I hope that you don't work in an office building downtown then.

Don't fly or drive anywhere either. Don't go to nightclubs. or a million other things. NYC is a big city people die all the time, what are you still doing living there?

Actually Maria Isabel was killed in the morning. So if you're avoiding the park when it's dark because of her killing then you should really just stay out altogether.