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  2. Umbra, penumbra and antumbra - Wikipedia

    en.wikipedia.org/wiki/Umbra,_penumbra_and_antumbra

    An alternative definition is that the penumbra is the region where some or all of the light source is obscured (i.e., the umbra is a subset of the penumbra). For example, NASA's Navigation and Ancillary Information Facility defines that a body in the umbra is also within the penumbra. [2]

  3. Crepuscular rays - Wikipedia

    en.wikipedia.org/wiki/Crepuscular_rays

    Crepuscular rays are noticeable when the contrast between light and dark is most obvious. Crepuscular comes from the Latin word crepusculum, meaning "twilight". [2] Crepuscular rays usually appear orange because the path through the atmosphere at dawn and dusk passes through up to 40 times as much air as rays from a high Sun at noon.

  4. Camera obscura - Wikipedia

    en.wikipedia.org/wiki/Camera_obscura

    Evidence that light and color do not mingle in air or (other) transparent bodies is (found in) the fact that, when several candles are at various distinct locations in the same area, and when they all face an aperture that opens into a dark recess, and when there is a white wall or (other white) opaque body in the dark recess facing that ...

  5. Autokinetic effect - Wikipedia

    en.wikipedia.org/wiki/Autokinetic_effect

    In his book documenting the opening stages of the second Gulf War from his position embedded with the 1st Marine Reconnaissance Battalion, Evan Wright documents an incident during which, at night in the Iraqi desert, the Marines observed the lights of a town approximately 40 kilometers away. These lights appeared to be moving and were suspected ...

  6. Light characteristic - Wikipedia

    en.wikipedia.org/wiki/Light_characteristic

    A Morse code light is light in which appearances of light of two clearly different durations (dots and dashes) are grouped to represent a character or characters in the Morse Code. For example, "Mo(A)" is a light in which in each period light is shown for a short period (dot) followed by a long period (dash), the Morse Code for "A".

  7. Sunbeam - Wikipedia

    en.wikipedia.org/wiki/Sunbeam

    Buddha rays [2] God rays, used by some members of the computer graphics industry [10] Jacob's Ladder [2] Light shafts, sometimes used in the computer graphics industry, such as the game engine Unreal Engine [11] Ropes of Maui, originally taura a Maui – from the Maori tale of Maui Potiki restraining the sun with ropes to make the days longer [2]

  8. Alpenglow - Wikipedia

    en.wikipedia.org/wiki/Alpenglow

    Solar ray 1 is the lowest from the Sun – the Sun is set. Solar ray 2 is reflected in the (snow) clouds to the observer. Alpenglow (from German: Alpenglühen, lit. 'Alps glow'; Italian: enrosadira) is an optical phenomenon that appears as a horizontal reddish glow near the horizon opposite to the Sun when the solar disk is just below the horizon.

  9. Darkness - Wikipedia

    en.wikipedia.org/wiki/Darkness

    The Creation of Light by Gustave Doré. Darkness is the condition resulting from a lack of illumination, or an absence of visible light.. Human vision is unable to distinguish colors in conditions of very low luminance because the hue-sensitive photoreceptor cells on the retina are inactive when light levels are insufficient, in the range of visual perception referred to as scotopic vision.