Positioning a Garden Sundial

Positioning a Garden Sundial to read the time of day as accurately as possible requires some research and study. Sundials need to point in the direction of True North, and the style (either a sharp straight edge or thin rod, often located at the edge or tip of the gnomon) must be aligned with the Earth's rotational axis. Most garden sundials are horizontal and easier to position by design. Horizontal sundials can lay flat on either a pedestal or sturdy surface, and only need to be angled if designed for a latitude other than where it is being used. If the sundial is designed for a latitude of 40° and is being used at a latitude of 45°, then the sundial's plane will need to be tilted upwards 5° in order to align properly. Also remember that sundials are designed to read sun time, not clock time.

The Direction of True North

The direction of True North is not the same as the north magnetic pole, but instead is marked by the north celestial pole. True North is found at latitude 90°N, and is the direction along Earth's surface towards the North Pole.

A compass will work for small garden sundials, but is not very accurate. A compass only helps to locate the magnetic north, but this will serve the typical garden sundial perfectly well. Garden sundials are designed for function, but many owners are happy just to have a sundial that is close to accurate.

You can also position a true vertical object at exactly local noon and mark the shadow. You will want to find a reliable method of marking the shadow at the instant of local noon. You can also position your sundial so that there is no shadow shown at high noon. The shadow should appear to the left in the morning, and to the right in the afternoon.

The sun will appear at times to be faster and slower than our watches read, again because sun time and clock time are not the same. The sun appears "fast" from mid-April through mid-June, and early September through late December. When the sun appears "fast" it will reach sun-noon (be directly overhead) not at 12:00:00 by your watch, but a few minutes earlier. When you are setting up your horizontal sundial, you want to know the time the sun is directly overhead.

There are certainly more advanced methods of determining True North, and setting sundials for accuracy, but our horizontal garden sundials can be set using the methods above. You will enjoy watching how the shadows on your sundial change through the seasons and how sun time really works.

The Angle of the Gnomon

Garden and Armillary Sundials are often bought as gifts, and when traveling. Bringing home a sundial that was produced outside of your area of longitude will require you check the angle of the gnomon. For example, a sundial made for the south of Spain will have an angle of 37° and will not tell the correct time if it is set up with the horizontal dial plate in Birmingham, Alabama where latitude is 52.5°N. You should check the angle of your gnomon regardless of where it was purchased and is set up, just to be certain your sundial is ready to tell sun-time.

A common method for checking the angle of the gnomon is to measure the angle with a protractor, and then crosscheck your measurement to ensure that the hour lines have been laid out correctly. You can back-calculate the gnomon angle from the angles of the hour lines. For example, the angle of the 9am and 3pm hour lines from the noon line is 26°24 at 30°N, 29°50 at 35°N, 32°44 at 40°N, 35°16 at 45°N, 37°27 at 50°N, and 39°20 at 55°N). Additional information can be found through research for more complicated sundials and gnomons.

If your gnomon is indeed angled incorrectly for your geographical location, you can use a wedge to bring the gnomon parallel to the earth's axis.

Armillary Sundials operate differently than horizontal sundials. Armillary sundials keep track of time more accurately than a standard garden sundial, and most have a fixed gnomon style aligned with Earth's rotation axis, as well as a shadow-receiving surface symmetrical to the axis. Armillary sundials are equiangular with straight hour lines that are equally spaced apart. The gnomon is a bar or stretched wire parallel to the celestial axis, and the face is a semi-circle. To correct for longitude with an armillary sundial, rotate the dial surface by the difference in longitude without changing the gnomon.

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Sundials Brass Sundials Aluminum Sundials Armillary Sundial Cast Iron Sundials Combination Sundial and Birdbath Sundial Bases Sundials - Shop By Size Resources Positioning a Garden Sundial Garden Sundial Ideas in Garden Decor Furniture Hammocks Bird Houses Bird Feeders Arbors Garden Decor What's Hot!!!	Positioning a Garden Sundial Positioning a Garden Sundial to read the time of day as accurately as possible requires some research and study. Sundials need to point in the direction of True North, and the style (either a sharp straight edge or thin rod, often located at the edge or tip of the gnomon) must be aligned with the Earth's rotational axis. Most garden sundials are horizontal and easier to position by design. Horizontal sundials can lay flat on either a pedestal or sturdy surface, and only need to be angled if designed for a latitude other than where it is being used. If the sundial is designed for a latitude of 40° and is being used at a latitude of 45°, then the sundial's plane will need to be tilted upwards 5° in order to align properly. Also remember that sundials are designed to read sun time, not clock time. The Direction of True North The direction of True North is not the same as the north magnetic pole, but instead is marked by the north celestial pole. True North is found at latitude 90°N, and is the direction along Earth's surface towards the North Pole. A compass will work for small garden sundials, but is not very accurate. A compass only helps to locate the magnetic north, but this will serve the typical garden sundial perfectly well. Garden sundials are designed for function, but many owners are happy just to have a sundial that is close to accurate. You can also position a true vertical object at exactly local noon and mark the shadow. You will want to find a reliable method of marking the shadow at the instant of local noon. You can also position your sundial so that there is no shadow shown at high noon. The shadow should appear to the left in the morning, and to the right in the afternoon. The sun will appear at times to be faster and slower than our watches read, again because sun time and clock time are not the same. The sun appears "fast" from mid-April through mid-June, and early September through late December. When the sun appears "fast" it will reach sun-noon (be directly overhead) not at 12:00:00 by your watch, but a few minutes earlier. When you are setting up your horizontal sundial, you want to know the time the sun is directly overhead. There are certainly more advanced methods of determining True North, and setting sundials for accuracy, but our horizontal garden sundials can be set using the methods above. You will enjoy watching how the shadows on your sundial change through the seasons and how sun time really works. The Angle of the Gnomon Garden and Armillary Sundials are often bought as gifts, and when traveling. Bringing home a sundial that was produced outside of your area of longitude will require you check the angle of the gnomon. For example, a sundial made for the south of Spain will have an angle of 37° and will not tell the correct time if it is set up with the horizontal dial plate in Birmingham, Alabama where latitude is 52.5°N. You should check the angle of your gnomon regardless of where it was purchased and is set up, just to be certain your sundial is ready to tell sun-time. A common method for checking the angle of the gnomon is to measure the angle with a protractor, and then crosscheck your measurement to ensure that the hour lines have been laid out correctly. You can back-calculate the gnomon angle from the angles of the hour lines. For example, the angle of the 9am and 3pm hour lines from the noon line is 26°24 at 30°N, 29°50 at 35°N, 32°44 at 40°N, 35°16 at 45°N, 37°27 at 50°N, and 39°20 at 55°N). Additional information can be found through research for more complicated sundials and gnomons. If your gnomon is indeed angled incorrectly for your geographical location, you can use a wedge to bring the gnomon parallel to the earth's axis. Armillary Sundials operate differently than horizontal sundials. Armillary sundials keep track of time more accurately than a standard garden sundial, and most have a fixed gnomon style aligned with Earth's rotation axis, as well as a shadow-receiving surface symmetrical to the axis. Armillary sundials are equiangular with straight hour lines that are equally spaced apart. The gnomon is a bar or stretched wire parallel to the celestial axis, and the face is a semi-circle. To correct for longitude with an armillary sundial, rotate the dial surface by the difference in longitude without changing the gnomon.
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