Sundials for Desert Landscapes

Desert climates provide plenty of summer sunshine, so why not put some of that light to work? Sundials are are not only unique conversation peices, they're also functional. Provided the sundial is installed properly (and this is the key factor), it can keep quite accurate time.

Types of garden sundials

At its simplest a sundial consists of a dial plate -- usually a metal or stone tablet with marked off in hours -- and a gnomon -- a blade or post in the center of the dial plate that casts a shadow on the dial plate. Within this form there are several variations. The two main types are:

Horizontal
This is the type most people think of when they hear "sundial." The dial plate is horizontal and the gnomon projects upright from the dial plate. There's also the " reflected ceiling sundial," a form of horizontal sundial in which a mirror laid on a south-facing windowsill reflects the sun onto the ceiling. The hour lines are drawn on the ceiling.

Vertical
The vertical types, designed to be hung on walls, are commonly "direct south dials," meaning they face dew south. In a direct south dial the gnomon will be at an angle equal to the co-latitude of the location, and the hour lines, if delineated for local time on location, will be symmetrical near the vertical noon line.

Garden sundial designs

Some sundials are designed to sit on pedestal, while others can be placed directly on a table. The gnomon is often part of a small statue such as the wings dragonfly pictured on the dial. In addition to hour lines, the dial plate of may contain a design such as a frog or leaves, and many with carry an inscription around the dial plate. Brass is one of the most popular materials for sundials, but other materials are also used.

Setting up a sundial

In order to tell the correct local time, the gnomon must be parallel with the earth's axis, or in other words, it must point towards the celestial pole. In the northern hemisphere, this means that the gnomon should point at the Pole Star. If sundial is wasn't made for the place at which it is to be set up it will have to be corrected. For more on calibrating a sundial: http://adelie.harvard.edu/ed/Activities/Sundial.html