Sundial

Museo della Civiltà Contadina del Friuli Imperiale (Sundials courtyard)    

Photo n° 3

Calculations were made using the “SUNSPEC” model of the “Florida Solar Energy Center”. The quadrant on the left also shows the local solar time, diurnal lines, the height of the sun above the horizon (the number in the brackets indicates the optical air mass, that is the measure of the trajectory across the atmosphere taken by the rays of the sun, in respect to the length of the trajectory along the vertical line).

The right hand side quadrant also shows the local solar time, diurnal lines, and the sunbeams incidence angle in respect to the line perpendicular to the surface.