At the horizon, the average amount of refraction is 34 arcminutes , though this amount varies based on atmospheric conditions. Also, unlike most other solar measurements, sunrise occurs when the Sun's upper limb , rather than its center, appears to cross the horizon.
The apparent radius of the Sun at the horizon is 16 arcminutes. These two angles combine to define sunrise to occur when the Sun's center is 50 arcminutes below the horizon, or The timing of sunrise varies throughout the year and is also affected by the viewer's longitude and latitude, altitude, and time zone.
These changes are driven by the axial tilt of Earth, daily rotation of the Earth, the planet's movement in its annual elliptical orbit around the Sun, and the Earth and Moon's paired revolutions around each other. The analemma can be used to make approximate predictions of the time of sunrise.
- Summer solstice.
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In late winter and spring, sunrise as seen from temperate latitudes occurs earlier each day, reaching its earliest time near the summer solstice ; although the exact date varies by latitude. After this point, the time of sunrise gets later each day, reaching its latest sometime around the winter solstice. The offset between the dates of the solstice and the earliest or latest sunrise time is caused by the eccentricity of Earth's orbit and the tilt of its axis, and is described by the analemma , which can be used to predict the dates.
Variations in atmospheric refraction can alter the time of sunrise by changing its apparent position.
Near the poles, the time-of-day variation is exaggerated, since the Sun crosses the horizon at a very shallow angle and thus rises more slowly. Accounting for atmospheric refraction and measuring from the leading edge slightly increases the average duration of day relative to night. The sunrise equation , however, which is used to derive the time of sunrise and sunset, uses the Sun's physical center for calculation, neglecting atmospheric refraction and the non-zero angle subtended by the solar disc.
Neglecting the effects of refraction and the Sun's non-zero size, whenever sunrise occurs, in temperate regions it is always in the northeast quadrant from the March equinox to the September equinox and in the southeast quadrant from the September equinox to the March equinox. Air molecules and airborne particles scatter white sunlight as it passes through the Earth's atmosphere.piobookdistbofa.gq/dynamics/ready-to-take-a-chance-again.pdf
Each red circle is a distinct line of latitude and represents a minute increase or decrease in daylight. Cities connected by the same line have the same number of daylight hours. On the June solstice, the sun always rises and sets at its northernmost point on the horizon. The farther you get from the equator, the closer sunrise and sunset appear due north on a compass.
The exact time of sunrise and sunset depends on two things: In Washington, sunrise and sunset on June 21 are at 5: Here are two more maps that show the time of sunrise and sunset across North America. Both take into account the effect of time zones and latitude, hence the interesting patchwork of colors.
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The first map shows sunrise times across North America. Many parts of the Lower 48 see sunset between 8: High enough to recommend sunscreen!
Although the summer solstice is the longest day of the year for that hemisphere, the dates of earliest sunrise and latest sunset vary by a few days. Although the sun appears at its highest altitude from the viewpoint of an observer in outer space or a terrestrial observer outside tropical latitudes, the highest altitude occurs on a different day for certain locations in the tropics, specifically those where the sun is directly overhead maximum 90 degrees elevation at the subsolar point.
This day occurs twice each year for all locations between the Tropic of Cancer and Tropic of Capricorn because the overhead sun appears to cross a given latitude once before the day of the solstice and once afterward. For all observers, the apparent position of the noon sun is at its most northerly point on the June solstice and most southerly on the December solstice.
Happy summer solstice! Here’s a guide to the longest day of the year.
The significance given to the summer solstice has varied among cultures, but most recognize the event in some way with holidays , festivals , and rituals around that time with themes of religion or fertility. In other cultural conventions, the solstice is closer to the middle of summer. Solstice is derived from the Latin words sol sun and sistere to stand still.
The following tables contain information on the length of the day on the summer solstice of the northern hemisphere and winter solstice of the southern hemisphere i.
Summer (Sunrise, #2) by Karen Kingsbury
The data was collected from the website of the Finnish Meteorological Institute on 20 June  as well as from certain other websites. The data is arranged geographically and within the tables from the longest day to the shortest one. From Wikipedia, the free encyclopedia. For other uses, see Summer solstice disambiguation.
Related Summer: 2 (Sunrise)
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