of the titles of this article is ambiguous. For further meanings see day (term clarifying).

The day (old high German: Time, where the sun burns) designates the following circumstances:

  • Day, a unit of the time
  • calender date, the current date.
  • Light day, the sun-illuminated („lightlight “) time tags - in contrast to the night - from sunrise to sunset.
  • Subjective day, the time interval from rising to the sleeping going.

This meaning difference leads to the fact that also the beginning oneCalender date in different cultural context one sets differently.

Time: To today, the current day related, designates yesterday the past and tomorrow the following day.

Table of contents

the SI day

time measure: In the measurement the day formulaful described as

SI - a unit of the time
the unit symbol: D
symbol for physical dimension time is: t.
1 D = 24 h = 1440 min = 86400 s

calender date

time interval: In the calendar calculation (the common Gregorian calendar) the time intervalfrom a midnight to the next midnight.

One time interval of 24 hours, which begins around 00:00 and ends around 24:00. 24:00 clock falls with the beginning of the next daily together (ISO 8601)

in the Jewish calendar and The day covers Islamic calendars the time of a sunset up to the next sunset. This view was in Europe altogether for a long time prevailing. The Roman counting of the night hours (vigiliae) and certain elements of the Christian rite can as examplesare called.

Day designates also generally special calender dates in a context, for instance the working day, in the distinction of time measure and time interval thus the working-day or the pure work time, and does not cover then no more 24 hours.

Astronomical days

in the astronomy are further, to the calender date similar sizes, which have their origin in the complex movements of the heavenly bodies and the different points of reference of sky-mechanical computations:

True sun day
the time interval from a sun highest level to the next sun highest level. Upthe sun day is based the Sonnenzeit, that is „the true local time “.
Middle sun day or civil day
that is identical into for instance the annual average of the true sun days and (almost) to the calender date: The yearly length becomes occasional by inserting from switching secondscorrected. These adjustments synchronize the calendar which is based on day night cycles that rotary earth with the tropical year which are based on the earth revolution around the sun and the instrumentation year, thus the world time with the universal time and the atomic time.
Star day or Sideri day
the revolution time of the earth regarding the fixed stars. It is based on the sidereal time.
Duration: 23 hours, 56 minutes and 4 seconds
of Ephemeridentag
the day, on the Ephemeridensekunde and/or. the Ephemeridenzeit develops

special meaning hasand/or. the sunning and sidereal time of the Nullmeridians for the definition of the world time or to the indication of star places had.

the lights day

light day one names the time period of a calender date, which is enough from sunrise to sunset.

The civil routine of the day is divided into the sections night, morning, morning, noon and/or. Noontime, afternoon, evening and midnight.

The borders between these sections are flowing and both from the culture area, the Zahreszeiten and of thatpersonal life circumstances affects. Partially also the dawn times are also included into the light day.

  • To the term light tags corresponds the astronomical term „to day elbow of the sun “.

The light day is strongest Kraft, those the internal clocks of theHumans synchronizes.

the subjective day

in the daily life is determined the subjective day by the rhythm by rising and sleeping going.

For the predominant Mehrzehl of humans the three different aspects collapse. However the fact actually results in,that one must rise in the winter term „before daybreak “, thus the routine of the day with the light day does not correspond, a contradiction, which can lead to such phenomena like the winter depression. This effect is moderated by the summer time something.

Is less easythe situation for humans, whose subjective day does not follow often or regularly the civil routine of the day, so for instance with work in layer. Such persons call intuitively the time after midnight to the preceding day duly. The shift to the calender date fallsonly about when writing written dates up, there communication to - sleeping - the remaining society is reduced. The contradiction is more problematic to the light day, that to health disturbances („shiftworker syndromes “) to lead can or with the guard service the feared Dog guard causes. Finally confusing is however the situation, if the personal day shifts so far that it overlaps with the next „social day “, as it can occur with extreme shift work or serious sleep disturbances. Humans, their personal day as life-stylepermanently, calls one is shifted against the light day night human being.

A further contradiction results from the contact with other time belts. During communication with humans, whose local time is considerably shifted against the own, is a clarification,which day is there straight, indispensably. In the modern computer-supported life by time belt clocks , or the function is supported that enamels are dated into UTC and converted only locally. With remote journeys into other time belts steps due to the Desynchronisation of the insideClock with different local light day jet-lay up.

see also

Wikipedia on the left of to the group of topics calendar and time

Article for the chronology of mankind:
linear units of the time calculation cyclic units of the time calculation
millenium century decade year (calendar) month week day (Calendar)
starting from 10. Millenium v. Chr. starting from 40. Century v. Chr. starting from 390er v. Chr. starting from 400 v. Chr. 1. January to 31. December
further articles about time:
An overview of entire geologic history offers those Geological time scale.
From the Big Bang to the emergence of the earth see early history of the universe.
For the units of time measurement see: Second, minute, hour.

Web on the left of

Wiktionary: Day - word origin, synonyms and translations
Wikiquote: Day - Quotations

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