I looked up some sunset and sunrise times today comparing Cambridge MA
to Boca Raton FL.
I understand why the sunset is later in Boca (it's further West, sees
the sun go down later), but that's only by 7 minutes.

Why is the sunRISE so much later (more than an hour later) there than
in Cambridge MA? If the length of day is the same, shouldn't Boca's
sunrise by 7 minutes later than Cambridge's?
Look at the 8/7/09 times and you'll see what I mean. Can the tilt
of the earth at this time of year give MA quite that much more daylight
than a point (globally speaking) not that much further South?

From what I can see the time from sunrise to sunset for Cambridge is
14:12 and for Boca Raton, only (oddly enough) 13:14.

Explanation?

This topic and the mere mention of the word "tilt" will elicit extended
essays of nonsense from certain parties in this forum. You've been warned.

Can the tilt
of the earth at this time of year give MA quite that much more daylight
than a point (globally speaking) not that much further South?

Yes. Boca Raton is almost exactly 16 deg south of Cambridge. People from
northern latitudes often remark about shorter summer days and quicker
sunrises and sunsets at low latitudes. It's very noticeable.
--
Curtis Croulet
Temecula, California

The Name wrote:

I looked up some sunset and sunrise times today comparing Cambridge MA
to Boca Raton FL.
I understand why the sunset is later in Boca (it's further West, sees
the sun go down later), but that's only by 7 minutes.

Why is the sunRISE so much later (more than an hour later) there than
in Cambridge MA? If the length of day is the same, shouldn't Boca's
sunrise by 7 minutes later than Cambridge's?

The duration of daylight isn't the same in Boca and Cambridge.

It's only a coincidence that the sunrise times are nearly identical.
If you were comparing the rise and set times in Cambridge with thoe
for at a point on the same line of longitude down in the middle of the
Bermuda Triangle, then the rise and set times would be symmetrical
about local noon, so to speak--but the difference in daylight duration
would be just as great.

Look at the 8/7/09 times and you'll see what I mean. Can the tilt
of the earth at this time of year give MA quite that much more daylight
than a point (globally speaking) not that much further South?

Yep. Go far enough North this time of year and the Sun never sets. Go
far enough south (to the equator) and the day is always the same
duration as night (hence the name of that particular parallel).
--
Dave

Dave Typinski wrote:

The Name wrote:

I looked up some sunset and sunrise times today comparing Cambridge MA
to Boca Raton FL.
I understand why the sunset is later in Boca (it's further West, sees
the sun go down later), but that's only by 7 minutes.

Why is the sunRISE so much later (more than an hour later) there than
in Cambridge MA? If the length of day is the same, shouldn't Boca's
sunrise by 7 minutes later than Cambridge's?

The duration of daylight isn't the same in Boca and Cambridge.

It's only a coincidence that the sunrise times are nearly identical.

Whoops. Change that to concidental sunset times.
--
Dave
A poor multitasker

On Aug 7, 6:42*pm, The Name wrote:
I looked up some sunset and sunrise times today comparing Cambridge MA
to Boca Raton FL.
I understand why the sunset is later in Boca (it's further West, sees
the sun go down later), but that's only by 7 minutes.

Why is the sunRISE so much later (more than an hour later) there than
in Cambridge MA?

Cambridge is at roughly 71 degrees West

Boca Raton is at 80 degrees West

With 4 minutes of clock time equating to 1 degree of geographical
separation,the 9 degree longitude difference between Cambridge and
Boca Raton equates to 36 minutes of clock time.On the Equinox ,when
the circle of illumination splits the geographical poles and all
locations on the planet experience equal amounts of daylight and
darkness,the transition from daylight to darkness will be 36 minutes
later in Boca Raton than in Cambridge.This is your benchmark for
working with all other data such as seasonal variations swings in
daylight and darkness at different latitudes with Cambridge
experiencing longer darkness in winter and longer daylight in summer
while Boca Raton experiences a more rapid transition between daylight
and darkness as it is rotating faster at that latitude while Cambridge
experiences a longer twilight.










* If the length of day is the same, shouldn't Boca's
sunrise by 7 minutes later than Cambridge's?

The length of the day is strictly the total length of time it takes
the Earth to turn from one noon to the next regardless of latitude and
as long as the Sun is visible with each cycle (polar regions are
exempt for this reason).This length has nothing to do with
hemispherical variations in length between daylight and darkness that
I assume you mean,it is purely a time measurement insofar as any given
location in the Northern or Southern hemisphere that share the same
longitude meridian will complete the noon cycle at the same moment -

http://montgomerycollege.edu/Departm...rthLatLong.gif




Look at the 8/7/09 times and you'll see what I mean. * Can the tilt
of the earth at this time of year give MA quite that much more daylight
than a point (globally speaking) not that much further South?


Using the Equinox as a starting point,Cambridge will enter the orbital
shadow 36 minutes before Boca Raton.As there is a wider seasonal swing
in daylight/darkness further North,Cambridge will enter the orbital
shadow much sooner around December and much later in June due to the
changing orbital orientation of the planet which in turn changes the
relationship between daily rotational characteristics and the circle
of illumination.

The last statement is based on treating daily rotation and orbital
motions separately rather than trying to explain what is occuring
using 'tilt'.The Earth rotational orientation remains constant
throughout the year and does not cause seasonal variations in daylight
and darkness,it is the specific way the Earth orbits the Sun that
causes seasonal variations and causes the natural noon cycles to
vary.Only through the power of modern imaging and the unique features
of Uranus is it now possible to see how daily and orbital motions
combine to explain what occurs here on Earth -

http://hubblesite.org/newscenter/arc...999/11/video/b

To get a real feel for what is going on,it is much better to look at
locations that are close to the geographical poles and the other close
to the Equator in order to appreceate what is happening between Boca
Raton and Cambridge further North in terms of the daily differences in
daylight,in the following almanac in Northern Norway,daylight will be
a whopping 14 minutes shorter than yesterday while close to the
Equator in Kenya, the difference is 1 second -

http://www.wunderground.com/cgi-bin/...ery=hammerfest

http://www.wunderground.com/cgi-bin/...query=Nanyuki+



*From what I can see the time from sunrise to sunset for Cambridge is
14:12 and for Boca Raton, only (oddly enough) 13:14.

Explanation?

As you posted to sci.astro.amateur,there are a lot of geostatic
astrologers who love this sort of thing and will dutifully ignore
planetary dynamics and give you and explanation based on the motion
of the Sun.The initial difficulties and unfamiliarities with an
explanation based on planetary dynamics disappear and you will get a
great satisfaction if you try to find your own answer ,it is also
quite important.

On Aug 7, 7:03*pm, "Curtis Croulet"
wrote:
This topic and the mere mention of the word "tilt" will elicit extended
essays of nonsense from certain parties in this forum. *You've been warned.

Can the tilt
of the earth at this time of year give MA quite that much more daylight
than a point (globally speaking) not that much further South?

Yes. *Boca Raton is almost exactly 16 deg south of Cambridge. *People from
northern latitudes often remark about shorter summer days and quicker
sunrises and sunsets at low latitudes. *It's very noticeable.
--
Curtis Croulet
Temecula, California

Good to see that you have learned something ( even without the
graitude).

Give him the speeds per hour and then you will certainly be my star
pupil -

http://www.ncgia.ucsb.edu/education/...s/table02.html

Those distances for 1 degree at different latitudes represent
rotational speeds in 4 minutes so that Boca Raton is rotating rapidly
into the orbital shadow hence the rapid transition into darkness
compared to Cambridge.

oriel36 wrote:

On Aug 7, 7:03*pm, "Curtis Croulet"
wrote:
This topic and the mere mention of the word "tilt" will elicit extended
essays of nonsense from certain parties in this forum. *You've been warned.

Those distances for 1 degree at different latitudes represent
rotational speeds in 4 minutes so that Boca Raton is rotating rapidly
into the orbital shadow hence the rapid transition into darkness
compared to Cambridge.

Aaaaaaaaaaaaaaaand, away we go!
--
Dave

On Aug 7, 8:17*pm, Dave Typinski wrote:
oriel36 wrote:

On Aug 7, 7:03*pm, "Curtis Croulet"
wrote:
This topic and the mere mention of the word "tilt" will elicit extended
essays of nonsense from certain parties in this forum. *You've been warned.

Those distances for 1 degree at different latitudes represent
rotational speeds in 4 minutes so that Boca Raton is rotating rapidly
into the orbital shadow hence the rapid transition into darkness
compared to Cambridge.

Aaaaaaaaaaaaaaaand, away we go!
--
Dave

Epicycle Dave , it is basic arithmetic that the Earth turns at a rate
of 111.32 km every 4 minutes/1 degree at the Equator,1669.8 km every
hour/15 degrees and the entire Equatorial circumference of 40,075 km
every 24 hours/360 degrees-

http://www.ncgia.ucsb.edu/education/...s/table02.html

Just to let the guys in the other forums know, how dumb the guys in
sci.astro.amateur actually are ,give them your value for rotation
through 15 degrees.

On Aug 7, 11:52*am, oriel36 wrote:

The last statement is based on treating daily rotation and orbital
motions separately rather than trying to explain what is occuring
using 'tilt'.The Earth rotational orientation remains constant
throughout the year and does not cause seasonal variations in daylight
and darkness,it is the specific way the Earth orbits the Sun that
causes seasonal variations and causes the natural noon cycles to
vary.Only through the power of modern imaging and the unique features
of Uranus is it now possible to see how daily and orbital motions
combine to explain what occurs here on Earth -

Your eyes are brown, aren't they? They must be, because you are so
full of **** that they couldn't possibly be any other color.

The Earth's orientation is constant with respect to the fixed stars,
but is constantly changing with respect to the sun, we call this tilt,
and this is what causes the seasons. You have completely
misinterpreted the Modern Imaging that you are so proud of, it is
laughable.

Since you are completely unteachable, you will never understand
frames, and so you are sunk.

On Aug 7, 12:03*pm, "Curtis Croulet"
wrote:
This topic and the mere mention of the word "tilt" will elicit extended
essays of nonsense from certain parties in this forum. *You've been warned.

By "this forum" sci.astro.amateur is being referred to.

Incidentally, I saw this news item:

http://www.sciencedaily.com/releases...0806141512.htm

so astronomers, misled though they are by Newtonian empiricism, do
think they know what caused the Ice Ages now.

John Savard