Ultraviolet sundial
OwnerJohn E. Adairinventor
Life of this patent
Estimating the term…
Abstract
A device for indicating the percentage of ultraviolet radiation which reaches the earth's surface for a given position of the Sun's altitude. The device consists of a planar member having a gnomon-like member affixed within its center. The gnomon-like member marks the center of nine (9) spaced concentric rings inscribed on a top surface of the planar member. The innermost circle is labeled 90%, the second 80% and so on to an outer edge. The radius for the circumference of each ring is calculated by a mathematical formula which correlates the altitude of the sun with a percentage amount of UV-B that reaches the surface of the earth.
Claims18
A device for indicating ultraviolet radiation comprising:
- a planar member having a plurality of spaced concentric rings on a top surface thereof, said concentric rings each defining an inscribed circumference for indicating a percentage of ultraviolet radiation;
- and
- a gnomon-like member supported in about a center of said planar member and projecting into a plane perpendicular to said planar member whereby said gnomon like member has a height relative to said concentric rings adapted to the casting of a shadow across said concentric rings when said device is in ambient sunlight thereby indicating the percentage of ultraviolet radiation corresponding to the sun's altitude relative to said planar member.
A device for indicating ultraviolet radiation comprising:
- a planar member having a plurality of spaced concentric rings on a top surface thereof, said concentric rings each defining an inscribed circumference for indicating a percentage of ultraviolet radiation;
- and
- a gnomon-like member supported in about a center of said planar member and projecting into a plane perpendicular to said planar member whereby said gnomon-like member having an approximate height H relative to radii R of said concentric rings approximated by the equation:
- ##EQU3## where I is the UV-B radiation intensity at sun angle alpha and I.sub.z is the UV-B radiation intensity at sun zenith,
- wherein said gnomon-like member is adapted to the casting of a shadow across said concentric rings when said device is in ambient sunlight thereby indicating the percentage of ultraviolet radiation corresponding to the sun's altitude relative to said planar member.
An apparatus for indicating ultraviolet radiation comprising a cylindrical disk having a plurality of spaced concentric rings on a top surface thereof, said plurality of concentric rings comprising nine (9) concentric rings defining inscribed circumferences labeled 90% to 10% in 10% increments, wherein the innermost inscribed circumference is 90% and the outermost inscribed circumference is 10%, said inscribed circumferences for indicating a percentage of ultraviolet radiation;
- a cylindrical rod supported in and about a center of said cylindrical disk and projecting into a plane perpendicular to said cylindrical disk, wherein said cylindrical rod having an approximate height H relative to said concentric rings adapted to the casting of a shadow across said concentric rings having radii R approximated by the equation:
- ##EQU4## where I is the UV-B radiation intensity to sun angle alpha and I.sub.z is the UV-B radiation intensity at sun zenith,
- whereby said device in the presence of ambient sunlight indicates the percentage of ultraviolet radiation corresponding to the sun's altitude relative to said cylindrical disk.
Dependencies are inferred from the claim text.