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World map showing the areas of Earth receiving daylight around 13:00 UTC in April. Daylight is the combination of all direct and indirect sunlight during the daytime.This includes direct sunlight, diffuse sky radiation, and (often) both of these reflected by Earth and terrestrial objects, like landforms and buildings.
The International Day of Light is celebrated each year on May 16. Its purpose, per UNESCO, is to strengthen cooperation and leverage its potential to foster peace and development. [1] Light-based technologies play an important role in education, science, art, culture, sustainable development, communications, energy and medicine.
The length of the light and dark in each phase varies across the seasons due to the tilt of the earth around its axis. The photoperiod defines the length of the light, for example a summer day the length of light could be 16 hours while the dark is 8 hours, whereas a winter day the length of day could be 8 hours, whereas the dark is 16 hours.
There are no actual daylight light sources, only simulators. Constructing a practical light source that emulates a D-series illuminant is a difficult problem. The chromaticity can be replicated simply by taking a well known light source and applying filters, such as the Spectralight III, that used filtered incandescent lamps. [22]
The Light of Day metaphorically refers to daylight. The Light of Day or Light of Day may also refer to: Light of Day, a 1987 film starring Michael J. Fox and Joan Jett "Light of Day" (song), the title song from the film, written by Bruce Springsteen; The Light of Day (Eric Ambler novel), a 1962 novel by Eric Ambler
[1] [2] In a descriptive sense, the term light pollution refers to the effects of any poorly implemented lighting sources, during the day or night. Light pollution can be understood not only as a phenomenon resulting from a specific source or kind of pollution, but also as a contributor to the wider, collective impact of various sources of ...
The daily light integral (DLI) is the number of photosynthetically active photons (photons in the PAR range) accumulated in a square meter over the course of a day. It is a function of photosynthetic light intensity and duration (day length) and is usually expressed as moles of light (mol photons) per square meter (m −2) per day (d −1), or: mol·m −2 ·d −1.
A light-minute is 60 light-seconds, and so the average distance between Earth and the Sun is 8.317 light-minutes. The average distance between Pluto and the Sun (34.72 AU [5]) is 4.81 light-hours. [6] Humanity's most distant artificial object, Voyager 1, has an interstellar velocity of 3.57 AU per year, [7] or 29.7 light-minutes per year. [8]