Both the upper and lower tangent arc form when hexagonal rod-shaped ice crystals in cirrus clouds have their long axis oriented horizontally. Each crystal can have its long axis oriented in …

Dec 16, 2024 · As the sun ascends above 29º, the upper and lower tangent arcs merge, forming a single halo that encircles the sun entirely. This halo is known as the "circumscribed halo," …

Dec 14, 2024 · Three phenomena in this tangent-arc category include the upper tangent arc, the lower tangent arc, and the circumscribed halo. We will examine the optics of upper tangent …

Upper and lower tangent arcs and a faint 22º halo. HaloSim3 simulation. The region below the horizon is dark blue. Tangent arcs alter shape as the sun's altitude changes. Mouse slowly …

The shape of an upper tangent arc varies with the elevation of the sun; while the sun is low (less than 29–32°) it appears as an arc over the sun forming a sharp angle. As the sun rises, the …

Dec 16, 2024 · This article explores the rare atmospheric optics phenomenon of Parry and Upper Tangent Arcs, discussing their formation, changes in shape with the sun's ascent, and the role …

When the angle of the Sun above the horizon is 30° or higher, the ends of the upper and lower tangent arcs will have curved around the Sun so much that they appear to join together to form …

Upper arc. The shape of an upper tangent arc varies with the elevation of the Sun; while the Sun is low (less than 29–32°) it appears as an arc over the observed Sun forming a sharp angle. …

Singly oriented column crystal with upper and lower Tangent Arc rays. The rays enter a prism side face and leave through another inclined 60º to the first. The best tangent arcs wing outwards …

The most common of these are the upper and lower tangent arcs to the halo of 22°. They form separate arcs when the sun is low, but as the sun climbs they join to produce the …