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Anticrepuscular rays, or antisolar rays, [1] are meteorological optical phenomena similar to crepuscular rays, but appear opposite the Sun in the sky. Anticrepuscular rays are essentially parallel, but appear to converge toward the antisolar point, the vanishing point, due to a visual illusion from linear perspective. [2] [3]
The antisolar point is the abstract point on the celestial sphere directly opposite the Sun from an observer's perspective. [1] This means that the antisolar point lies above the horizon when the Sun is below it, and vice versa. On a sunny day, the antisolar point can be easily found; it is located within the shadow of the observer's head.
Loosely, the term crepuscular rays is sometimes extended to the general phenomenon of rays of sunlight that appear to converge at a point in the sky, irrespective of time of day. [ 3 ] [ 4 ] A rare related phenomenon are anticrepuscular rays which can appear at the same time (and coloration) as crepuscular rays but in the opposite direction of ...
The principal ray or chief ray (sometimes known as the b ray) in an optical system is the meridional ray that starts at an edge of an object and passes through the center of the aperture stop. [5] [8] [7] The distance between the chief ray (or an extension of it for a virtual image) and the optical axis at an image location defines the size of ...
These anticrepuscular rays appear to converge at the antisolar point, as viewed from an aircraft above the clouded ocean.. In some cases, sunbeams may extend across the sky and appear to converge at the antisolar point, the point on the celestial sphere opposite of the Sun's direction.
Comparison of positive and negative birefringence : In positive birefringence (figure 1), the ordinary ray (p-polarisation in this case w.r.t. magenta-coloured plane of incidence), perpendicular to optic axis A is the fast ray (F) while the extraordinary ray (s-polarisation in this case and parallel to optic axis A) is the slow ray (S).
When it comes to astrological compatibility, opposites really do attract.. The 12 signs of the zodiac are typically illustrated as sitting in a wheel. It may come as a surprise, but the signs ...
With respect to the AB ray, the AD ray is called the opposite ray. Thus, we would say that two different points, A and B, define a line and a decomposition of this line into the disjoint union of an open segment (A, B) and two rays, BC and AD (the point D is not drawn in the diagram, but is to the left of A on the line AB). These are not ...