Forumchem - Forum with AI(ALICE BOT & HAL9000) and TTS

On the 21st of march there will be equal sun and dark. I live as far north as Sweden. If I face the sun and then move 90degrees to the left,will that location be the "true north",or will the higher latitude make it NOT the true north

As Raymond says, refraction causes the sun to appear before it"s geometrically centred on the horizon (i.e. as it would appear if there were no atmosphere). Since the Sun is slanting to the right as it rises, it won"t be due east until several minutes after the "official" time of sunrise. This effect becomes more noticeable the farther you go from the equator. I ran my Starry Night planetarium program for Stockholm for 21st March 2010 and it gives the time of sunrise as 5:47:20 and the time at which the Sun is due east as 5:55:35, some eight minutes later.

I think you are missing a bit:

if I face the Sun AT SUNRISE

In theory, the sun rises exactly due East on the day of the equinox.

in practice, the refraction (an effect due to the atmosphere) causes the sun to rise a few degrees left of due East (for observers in the Northern hemisphere). That is because the refraction lifts the image of the Sun, making it appear a bit higher than it really is.

You have to wait for the Sun to be a bit more than its own diameter above the visible horizon (if you do have a flat horizon at the same level as where you are) before you can say the sun is now due East.

If you live near the equator, this is irrelevant (the azimuth of the Sun does not change while it rises). As you move north, the difference gets bigger and bigger.

You could be almost 5 degrees off if you simply take the first flash of sunlight as sunrise.

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The best kind of horizon for this is the sea horizon, while the observer is not far above the water surface, on a ship.

If you are very high relative to the horizon (e.g., standing on a cliff by the sea), then another factor, called dip makes it worst.

If you live West of a mountain range, you will have the opposite effect: by the time you see the Sun appear above the mountain range, you are well passed the theoretical sunrise.

I assume you mean at sunrise.

Here"s a calculator for sunrise and sunset.
http://www.timeanddate.com/worldclock/sunrise.html

When I do Stockholm for the month of March, I get this for Mar 21 for the azimuth display:
Mar 21, 20105:48 AM6:04 PM88°East272°West12h 16m 46s+ 5m 20s

So it"s 2 degrees away from East and West at sunrise and sunset. On the other hand, that day is also not exactly 12 hours.

I see this on the 18th:
Mar 18, 20105:56 AM5:57 PM91°East270°West12h 00m 44s+ 5m 20s