Does The Sun Ever Pass Round To The North Here?

[AmeriThai]

yes, I think you are all right if the earth is flat  

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You're not trying to say the earth is round, are you, you heretic?

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Nope its flat, and rides through space on the back of four giant chang, on the back of a celestial turtle ( With apologies in advance to Terry Pratchett) !!!!!!!!

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LOL!

http://www.alaska.net/~clund/e_djublonskop...arthsociety.htm

[Johpa]

For what it is worth, any good globe should have a figure-eight, usually out in Pacific away from other markings, that will show the path of the sun between the tropics. Figure it hits the equator twice a year on the equinoxes and hit the tropic lines on the respective solstices and you should be able to estimate the bi-annual solar max, the day the sun is directly overhead, for your neck of the woods if you happen to live between the tropics.

And yes, in Thailand between the two solar maxes in the summer, the sun casts a shadow to the south during midday.

[chownah]

If you made a sun chart on the northern and southern hemisphere solstice days. wouldn't this give you the minimum/maximum range?

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You are correct. It would show you where the sun was all throughout the day on the days when the sun was the highest angle and the lowest angle in the sky. By highest angle and lowest angle I mean the greatest angle and the smallest angle as measured from the south (assuming that you are north of the equator)...I say this because if you are in the tropics then the sun will actually get higher each day until it goes over the top..so to speak..when it actually reaches its highest point (can't get higher than directly overhead) and then proceeds to get lower in the sky until you get to the solstice when it changes course and starts getting higher in the sky each day until it gets to be directly overhead and is once again at its highest (can't get higher than directly overhead) and then proceeds to get lower again as the sun 'approaches' the equator.

It is so hard to explain this!!! That's why mathematical equations are so much simpler...I don't understand why no one wants to see these sweet, sexy, luscious equations....hahahhahahhaa

Edited August 26, 2005 by chownah

[Jai Dee]

It is so hard to explain this!!!  That's why mathematical equations are so much simpler...I don't understand why no one wants to see these sweet, sexy, luscious equations....hahahhahahhaa

C'mon then chownah... I'll bite your bait... let's all see them.

Sheesh... what am I letting myself in for?

[wilko]

Yes!

I like your methodology...that's more or less exactly what I was thinking...couldn't vouch for the maths though...not my bag. Still it looks as if it's back to watching a stick in the sand on Chawaeng beach for a few more hours to confirm. I did this with a Danish guy once, we got some very strange looks...2 guys sipping beer and peering at a stickfor hours on end, occsionally waving away bemused pedestrians....

I think A merry Thai has just woken up.........

[chownah]

Yes!

I like your methodology...that's more or less exactly what I was thinking...couldn't vouch for the maths though...not my bag. Still it looks as if it's back to watching a stick in the sand on Chawaeng beach for a few more hours to confirm. I did this with a Danish guy once, we got some very strange looks...2 guys sipping beer and peering at a stickfor hours on end, occsionally waving away bemused pedestrians....

I think A merry Thai has just woken up.........

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Good work, Wilko!! The stick in the sand is great!!! Who says scientific research has to be a grind. If your friends ask you what you did in Thailand you can tell them you studied computational astronomy!

[chownah]

It is so hard to explain this!!!  That's why mathematical equations are so much simpler...I don't understand why no one wants to see these sweet, sexy, luscious equations....hahahhahahhaa

C'mon then chownah... I'll bite your bait... let's all see them.

Sheesh... what am I letting myself in for?

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The equations have Greek letters...can I do that here? if so how?

[Jai Dee]

It is so hard to explain this!!!  That's why mathematical equations are so much simpler...I don't understand why no one wants to see these sweet, sexy, luscious equations....hahahhahahhaa

C'mon then chownah... I'll bite your bait... let's all see them.

Sheesh... what am I letting myself in for?

The equations have Greek letters...can I do that here? if so how?

Assuming you're serious, why not put them in a Word document and post it as an attachment?

I love to see mathematical engineering results!

[wilko]

Good work, Wilko!! The stick in the sand is great!!! Who says scientific research has to be a grind. If your friends ask you what you did in Thailand you can tell them you studied computational astronomy!

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I did?..er what??..oh yeah!

Or was it just astickal gazing?

[Sir Burr]

The equations have Greek letters...can I do that here?  if so how?

Try using ASCII characters. Press Alt and a three figure number.

eg Alt 248 =° (degree sign)

Alt 172 = ¼

Sorry, don't know the numbers for the greek letters, but I'm sure you could Google it.

Edited August 26, 2005 by Sir Burr

[Jai Dee]

If you are running Windows XP you can click Start, All Programs, Accessories, System Tools, Character Map, and select the Greek or other characters that you want.

The ASCII character equivalent is shown the lower right hand corner.

Hope this helps...

[DavieA]

If directly on the equator, depending on the time of year the sun goes round either to the North or the South....does anyone know if Thailand ever experiences this????

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hmmm, I think you have a small problem!!

Thailand is well north of the equator, just south of the tropic of Cancer

so no way would you see the sun behave like that

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Educated in Thailand?

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cheeky boy, I stand corrected!!

educated in Thailand true, but I wasn't listening a lot of the time, esp. when the sun was out and overhead somewhere

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Siam....you sound like most of my students! It's no wonder Thai students need extra classes everyday and on weekends to pass! lol

And to the rest of ya.... who cares!

Just be thankful you have a sun or you'd be dead! lol

Edited August 26, 2005 by DavieA

[chownah]

Well I've tried to get the Greek letters to work but have had no success but I have another plan...I'll just write in the name of the Greek letter wherever it is used...so here goes. All of this stuff came off of the internet along time ago so I don't remember where.

You need three equations:

Equation #1

sin (a) = sin (phi) * sin(delta) + cos (phi) * cos (delta) * cos (h)

and

Equation #2

sin (alpha) = -cos (delta) * sin (h) / cos (a)

and

Equation #3

delta = 23.45 * sin (360*(284+N) / 365)

Note: 23.45 is the latitude of the tropics of cancer and capricorn measured in degrees.

Next I will define what all the variable mean in the order that they appear in the equations above:

a = the altitude of the sun, also described as the angular elevation of the sun above the horizon.

phi = the latitude of the observer, also described as the latitude of the place for which you are making the sun chart.

delta = the declination of the sun, also described as the angular distance the sun appears to be either north or south of the equator...for example, for the northern solstice delta = 23.45 degrees, at both equinoxes delta = 0 degrees.

h = the hour angle of the sun, also described as the angular distance to the sun from the meridian of the observer...noon = 0 degrees, 1:00pm = 15degrees, 2:00 = 30 degrees, etc.

alpha = the azimuth of the sun, also described as the horizontal distance measured eastward from north to the sun.

N = the day number, also described as which day of the year is the day for which you want to make the sun chart, for example for Jan 1, N=1...for Jan 2, N=2...for Feb 1, N=32....for Dec 1 N=335.......for Dec 31, N=365..Note: this system of equations does not account for leap year...this system is used for siting buildings etc. and if you need rocket science accuracy then it works basically the same but you use fractional day numbers and you need to know what the fractional day is that starts the year...forget it unless you're wanting to predict timing for a moon shot.

Instructions:

1. Choose the day of the year for which you want to make the sun chart and find out what "N" is for that day.

2. Decide what time of the day you want to calculate for first and find "h" for that hour.

3. Find the latitude of the location for which you want to make the sun chart...this is the "phi".

4. Using "N", calculate "delta".

5. Using "delta", "phi", and "h"...all of which you know by now...compute "a"...."a" is one of the things you are trying to find...it is the altitude of the sun at the location of interest on the day of interest at the hour of interest.

6. Using "a", "h", and "delta" calculate "alpha"....."alpha" is one of the thilngs you are trying to find...it is the azimuth of the sun at the location of interest on the day of interest at the hour of interest.

There you've calculated the first point on your sun chart....calculate a point for every hour of the day and smoothly connect the dots and you've got a sun chart for the location of interest on the day of interest. If you know how to use Excel spread sheets or the like you can fairly easily create a spread sheet to calculate all the data points you need very quickly...if you do it by hand it will take a while...happy computing!

I'm going to post this and look for errors later!

Edited August 26, 2005 by chownah

[PeaceBlondie]

The neat thing about living well into the tropics - Hua Hin is near 12 degrees north, roughly halfway between the Equator and the Tropic of Cancer - is that the sun is NOT directly overhead on June 23. Then, the sun at noon is about 11 degrees north. There are two times each summer when the sun is directly overhead in the tropics. For Hua Hin, which is not far south of Bangkok, it's about August 20 and April 26.

But ten degrees to the north or south of directly overhead is all pretty much the same. Thus, for six months in central Thailand, the sun is virtually overhead at midday.

The earth does not wobble; it's just on an axis that's permanently tilted in relation to its orbit facing the sun.

Most natives of tropical climates hardly notice the difference in the length of days from June to December, since it's maybe a range from 13 to 11 hours.

Sunrise and sunset in the tropics occurs much more quickly than it does far from the Equator. Somebody in Edinburgh, Scotland might watch the sun set slowly, at an angle. At Phuket, it just drops quickly into the sea, straight down.

One last thing, and then class is dismissed. The earth rotates at a constant rate around the sun, but the degrees of the sun above the equator follow a sine curve. For most of June or December, everywhere in the world, the inclination of the sun is almost constant from one day to the next. Around the equinoxes, however, the degrees (and length of days) is changing at a rapid pace, especially in the Arctic and Antarctic regions.

Edited August 26, 2005 by PeaceBlondie

[AmeriThai]

The earth does not wobble; it's just on an axis that's permanently tilted in relation to its orbit facing the sun.

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Earth: Tilt & Wobble

There’s always something new for people to learn and I’m no exception. The tilt of the Earth may have been caused by a collision early in the Earth’s history. If I’m not mistaken, the tilt of the Earth is in a fixed position at 23.5 degrees as it orbits around the sun. It might vary a little bit, but it would be very slight. Simply put, the Earth’s North Pole is tilting toward the sun at one time during the year, but halfway through its annual orbit it tilts away from the sun. To further complicate matters, the Earth is not on a circular orbit, but a slightly elliptical one. However, it’s remarkably close to circular.

Based on the illustrations below, a difference in the tilt seems to be apparent during the Equinoxes and the Solstices. I can’t see how that could be if the Earth is generally tilted at 23.5 degrees. Maybe someone can better explain what the heck we’re looking at here.

At the same time, the Earth does indeed wobble for a variety of reasons, including the gravitational tug of the sun and the moon, among other things, although it’s a slow process. However, the wobble in and by itself isn’t what causes changes in the sun’s position throughout the year.

For those who like getting into the geometrical calculations to explain the position of the sun throughout the year, feel free. For those who prefer more simple explanations or illustrations in visualizing what’s going on, here are a few interesting links.

TILT

Tilt of Earth = 23.5 degrees.

http://www.physicalgeography.net/fundamentals/6h.html

Equnox

Why is there more than 12 hours of daylight on the equinoxes? Why not an equal 12 hours of day and 12 hours of night at those times?

http://www.astronomycafe.net/qadir/q834.html

Seasons & Earth’s Orbit – Milankovitch Cycles

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

Earth-Sun Geometry

Nice graphics & chart

http://www.physicalgeography.net/fundamentals/6h.html

WOBBLE

Chandler Wobble

“The wobble is mainly caused by the Sun, Moon, and the larger planets, which apply a torque to the Earth. Other effects are caused by the movement of the Earth's crust and by air mass movement.

It is theorized that the reason the Earth is tilted on its axis is that soon after it was formed, it was hit by a large body.”

Does the Earth Wobble?

Answer: Yes.

http://www.windows.ucar.edu/tour/link=/kid...rth_motion.html

North Pole diagram showing Earth wobble

http://image.gsfc.nasa.gov/poetry/ask/q1725.html

Why Does the Earth wobble?

http://www.crystalinks.com/earthswobble.html

But I'll still volunteer myself to try some fresh roasted crow.