Sunset in the context of Sky brightness


Sunset in the context of Sky brightness

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⭐ Core Definition: Sunset

Sunset (or sundown) is the disappearance of the Sun at the end of the Sun path, below the horizon of the Earth (or any other astronomical object in the Solar System) due to its rotation. As viewed from everywhere on Earth, it is a phenomenon that happens approximately once every 24 hours, except in areas close to the poles. The equinox Sun sets due west at the moment of both the spring and autumn equinoxes. As viewed from the Northern Hemisphere, the Sun sets to the northwest (or not at all) in the spring and summer, and to the southwest in the autumn and winter; these seasons are reversed for the Southern Hemisphere.

The sunset is defined in astronomy as the moment the upper limb of the Sun disappears below the horizon. Near the horizon, atmospheric refraction causes sunlight rays to be distorted to such an extent that geometrically the solar disk is already about one diameter below the horizon when a sunset is observed.

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Sunset in the context of Almanac

An almanac (also spelled almanack and almanach) is a regularly published listing of a set of current information about one or multiple subjects. It includes information like weather forecasts, farmers' planting dates, tide tables, and other tabular data often arranged according to the calendar. Celestial figures and various statistics are found in almanacs, such as the rising and setting times of the Sun and Moon, dates of eclipses, hours of high and low tides, and religious festivals. The set of events noted in an almanac may be tailored for a specific group of readers, such as farmers, sailors, or astronomers.

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Sunset in the context of Night sky

The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon.

Natural light sources in a night sky include moonlight, starlight, and airglow, depending on location and timing. Aurorae light up the skies above the polar circles. Occasionally, a large coronal mass ejection from the Sun or simply high levels of solar wind may extend the phenomenon toward the Equator.

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Sunset in the context of Jersey Shore

The Jersey Shore, commonly called the Shore by locals, is the coastal region of the U.S. state of New Jersey. The term encompasses about 141 miles (227 km) of oceanfront bordering the Atlantic Ocean, from Perth Amboy in the north to Cape May Point in the south. The region includes Middlesex, Monmouth, Ocean, Atlantic, and Cape May counties, which are in the central and southern parts of the state. Located in the center of the Northeast Megalopolis, the northern half of the shore region is part of the New York metro area, while the southern half of the shore region is part of the Philadelphia metro area. The Jersey Shore hosts the highest concentration of oceanside boardwalks in the United States.

Famous for its wide beaches, and many boardwalks featuring arcades, amusement parks, and water parks, the Jersey Shore is a popular vacation spot for residents of North Jersey, New York, Maryland, Delaware, Connecticut, and Pennsylvania. Certain shore communities are also popular with visitors from the Canadian province of Quebec. Due to New Jersey's peninsular geography, both sunrise and sunset are visible over water from different points on the Jersey Shore.

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Sunset in the context of Night

Night, or nighttime, is the period of darkness when the Sun is below the horizon. Daylight illuminates one side of the Earth, leaving the other in darkness. The opposite of nighttime is daytime. Earth's rotation causes the appearance of sunrise and sunset. Moonlight, airglow, starlight, and light pollution dimly illuminate night. The duration of day, night, and twilight varies depending on the time of year and the latitude. Night on other celestial bodies is affected by their rotation and orbital periods. The planets Mercury and Venus have much longer nights than Earth. On Venus, night lasts about 58 Earth days. The Moon's rotation is tidally locked, rotating so that one of the sides of the Moon always faces Earth. Nightfall across portions of the near side of the Moon results in lunar phases visible from Earth.

Organisms respond to the changes brought by nightfall: darkness, increased humidity, and lower temperatures. Their responses include direct reactions and adjustments to circadian rhythms governed by an internal biological clock. These circadian rhythms, regulated by exposure to light and darkness, affect an organism's behavior and physiology. Animals more active at night are called nocturnal and have adaptations for low light, including different forms of night vision and the heightening of other senses. Diurnal animals are active during the day and sleep at night; mammals, birds, and some others dream while asleep. Fungi respond directly to nightfall and increase their biomass. With some exceptions, fungi do not rely on a biological clock. Plants store energy produced through photosynthesis as starch granules to consume at night. Algae engage in a similar process, and cyanobacteria transition from photosynthesis to nitrogen fixation after sunset. In arid environments like deserts, plants evolved to be more active at night, with many gathering carbon dioxide overnight for daytime photosynthesis. Night-blooming cacti rely on nocturnal pollinators such as bats and moths for reproduction. Light pollution disrupts the patterns in ecosystems and is especially harmful to night-flying insects.

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Sunset in the context of September equinox

The September equinox (or southward equinox) is the moment when the Sun appears to cross the celestial equator, heading southward. Because of differences between the calendar year and the tropical year, the September equinox may occur from September 21 to 24.

At the equinox, the Sun as viewed from the equator rises due east and sets due west. Before the Southward equinox, the Sun rises and sets more northerly, and afterwards, it rises and sets more southerly.

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Sunset in the context of Recreational fishing

Recreational fishing, also called sport fishing or game fishing, is fishing for leisure, exercise or competition. It can be contrasted with commercial fishing, which is occupational fishing activities done for profit; or subsistence fishing, which is fishing for survival and livelihood.

The most common form of recreational fishing is angling, which is done with a rig of rod, reel, line, hooks and any one of a wide range of baits, as well as other complementary devices such as weights, floats, swivels and method feeders, collectively referred to as terminal tackles. Lures are frequently used instead of fresh bait when fishing for predatory fishes. Some hobbyists hand-make custom tackles themselves, including plastic lures and artificial flies.

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Sunset in the context of Sawm

In Islam, fasting (called ṣawm in Arabic: صَوم [sˤɑwm], or ṣiyām صيام [sˤɪˈjæːm]) is the practice of abstaining from food, drink, sexual activity, and anything that substitutes food and drink. During the holy month of Ramadan, fasting is observed between dawn and sunset when the prayer call of the dawn prayer and the sunset prayer is called. Ramadan is the ninth month of the Muslim lunar calendar and fasting is a requirement for able Muslims as it is the fourth of the five pillars of Islam.

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Sunset in the context of Heliacal risings

The heliacal rising (/hɪˈl.əkəl/ hih-LY-ə-kəl) of a star or a planet occurs annually, when it becomes visible above the eastern horizon at dawn in the brief moment just before sunrise (thus becoming "the morning star"). A heliacal rising marks the time when a star or planet becomes visible for the first time again in the night sky after having set with the Sun at the western horizon in a previous sunset (its heliacal setting), having since been in the sky only during daytime, obscured by sunlight.

Historically, the most important such rising is that of Sirius, which was an important feature of the Egyptian calendar and astronomical development. The rising of the Pleiades heralded the start of the Ancient Greek sailing season, using celestial navigation, as well as the farming season (attested by Hesiod in his Works and Days). Heliacal rising is only one of several types of alignment for stars' risings and settings; mostly the risings and settings of celestial objects are organized into lists of morning and evening risings and settings. Culmination in the evening and the culmination in the morning are separated by half a year, while on the other hand risings and settings in the evenings and the mornings are only separated by a half-year at the equator, and at other latitudes set apart by different fractions of the year.

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Sunset in the context of West

West is one of the four cardinal directions or points of the compass. It is the opposite direction from east and is the direction in which the Sun sets on the Earth.

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Sunset in the context of Evening

Evening is the period of a day that begins at the end of afternoon and overlaps with the beginning of night. It starts when the sun is close to the horizon and overlaps both twilight and night. The exact times when evening begins and ends are subjective and depend on location and time of year. In some cases, evening is considered to begin during daylight; before sunset.

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Sunset in the context of Sea breeze

A sea breeze or onshore breeze is a wind that blows in the afternoon from a large body of water toward or onto a landmass. By contrast, a land breeze or offshore breeze is a wind that blows in the night from a landmass toward or onto a large body of water. Sea breezes and land breezes are both important factors in coastal regions' prevailing winds.

Sea breeze and land breeze develop due to differences in air pressure created by the differing heat capacities of water and dry land. As such, sea breezes and land breezes are more localised than prevailing winds. Since land heats up much faster than water under solar radiation, a sea breeze is a common occurrence along coasts after sunrise. On the other hand, dry land also cools faster than water without solar radiation, so the wind instead flows from the land towards the sea when the sea breeze dissipates after sunset.

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Sunset in the context of Sun path

Sun path, sometimes also called day arc, refers to the daily (sunrise to sunset) and seasonal arc-like path that the Sun appears to follow across the sky as the Earth rotates and orbits the Sun. The Sun's path affects the length of daytime experienced and amount of daylight received along a certain latitude during a given season.

The relative position of the Sun is a major factor in the heat gain of buildings and in the performance of solar energy systems. Accurate location-specific knowledge of sun path and climatic conditions is essential for economic decisions about solar collector area, orientation, landscaping, summer shading, and the cost-effective use of solar trackers.

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Sunset in the context of Twilight

Twilight is daylight illumination produced by diffuse sky radiation when the Sun is below the horizon as sunlight from the upper atmosphere is scattered in a way that illuminates both the Earth's lower atmosphere and also the Earth's surface. Twilight also may be any period when this illumination occurs, including dawn and dusk.

The lower the Sun is beneath the horizon, the dimmer the sky (other factors such as atmospheric conditions being equal). When the Sun reaches 18° below the horizon, the illumination emanating from the sky is nearly zero, and evening twilight becomes nighttime. When the Sun approaches re-emergence, reaching 18° below the horizon, nighttime becomes morning twilight. Owing to its distinctive quality, primarily the absence of shadows and the appearance of objects silhouetted against the lit sky, twilight has long been popular with photographers and painters, who often refer to it as the blue hour, after the French expression l'heure bleue.

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Sunset in the context of Cloud cover

Cloud cover (also known as cloudiness, cloudage, or cloud amount) refers to the fraction of the sky obscured by clouds on average when observed from a particular location. Okta is the usual unit for measurement of the cloud cover. The cloud cover is correlated to the sunshine duration as the least cloudy locales are the sunniest ones while the cloudiest areas are the least sunny places, as clouds can block sunlight, especially at sunrise and sunset where sunlight is already limited.

The global cloud cover averages around 67-68%, though it ranges from 56% to 73% depending on the minimum optical depth considered (lower when optical depth is large, and higher when it is low, such that subvisible cirrus clouds are counted). Average cloud cover is around 72% over the oceans, with low seasonal variation, and about 55% above land, with significant seasonal variation.

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Sunset in the context of Angle of incidence (optics)

The angle of incidence, in geometric optics, is the angle between a ray incident on a surface and the line perpendicular (at 90 degree angle) to the surface at the point of incidence, called the normal. The ray can be formed by any waves, such as optical, acoustic, microwave, and X-ray. In the figure below, the line representing a ray makes an angle θ with the normal (dotted line). The angle of incidence at which light is first totally internally reflected is known as the critical angle. The angle of reflection and angle of refraction are other angles related to beams.

In computer graphics and geography, the angle of incidence is also known as the illumination angle of a surface with a light source, such as the Earth's surface and the Sun. It can also be equivalently described as the angle between the tangent plane of the surface and another plane at right angles to the light rays. This means that the illumination angle of a certain point on Earth's surface is if the Sun is precisely overhead and that it is 90° at sunset or sunrise.

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Sunset in the context of Atmosphere of the Moon

The atmosphere of the Moon is a very sparse layer of gases surrounding the Moon, consisting only of an exosphere. For most practical purposes, the Moon is considered to be surrounded by vacuum. The elevated presence of atomic and molecular particles in its vicinity compared to interplanetary medium, referred to as "lunar atmosphere" for scientific objectives, is negligible in comparison with the gaseous envelopes surrounding Earth and most planets of the Solar System, and comparable to their exospheres. The pressure of this small mass is around 3×10 atm (0.3 nPa), varying throughout the day, and has a total mass of less than 10 metric tonnes. Otherwise, the Moon is considered not to have an atmosphere because it cannot absorb measurable quantities of radiation, does not appear layered or self-circulating, and requires constant replenishment due to the high rate at which its gases are lost into space.

Roger Joseph Boscovich was the first modern astronomer to argue for the lack of atmosphere around the Moon in his De lunae atmosphaera (1753).

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Sunset in the context of Afterglow

In meteorology, an afterglow is an optical phenomenon, generally referring to a broad arch of whitish or pinkish sunlight in the twilight sky after sunset, consisting of purple light and bright segment. It consists of several atmospheric optical phenomena. The purple light mainly occurs when the Sun is 2–6° below the horizon, during civil twilight (from sunset to civil dusk), while the bright segment lasts until the end of the nautical twilight. Similarly, a foreglow is a broad arch of whitish or pinkish sunlight in the twilight sky before sunrise, consisting of purple light and bright segment.

Afterglow is often seen in volcanic eruptions, in which the purple light might also be called volcanic purple light. In volcanic occurrences specifically, the light is scattered by fine particulates, like dust, suspended in the atmosphere. Afterglow may refer to the golden-red glowing light from the sunset and sunrise reflected in the sky in alpenglow (similar to the Belt of Venus) and in particularly for its last stage, when the purple light is reflected.

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Sunset in the context of Maghrib (prayer)

Maghrib (Arabic: صلاة المغرب) is one of the five mandatory salah (Islamic prayers), and contains three cycles (rak'a). If counted from midnight, it is the fourth one.

According to Shia and Sunni Muslims, the period for Maghrib prayer starts just after sunset, following Asr prayer, and ends at the beginning of night, the start of the Isha prayer. As for Shia Muslims, since they allow Maghrib and Isha prayers to be performed one after another, the period for Maghrib prayer extends until midnight. Sunni Muslims (Except for the Hanafi school) are also permitted to combine Maghrib and Isha prayers if they are traveling and incapable of performing the prayers separately. In this case, the period for Maghrib prayer extends from sunset to dawn, as with Shiites.

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