Different Types of Sundials
There are many types of sundials but they can be grouped into three main classes:
- Those having a gnomon parallel to the Earth's axis, and around which the Sun and all celestial bodies appear to move at a rate of 15º per hour. The earth turns 360º in about 24 hours, therefore the sun's apparent position moves 360/24 = 15º each hour.
- Those that depend on the altitude of the Sun above the horizon. These dials are known as altitude dials.
- Those that depend on the Sun's azimuth. They are known as azimuth dials.
These three classes of sundials can again be grouped into 2 different types:
- Pole - style