Daytime

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Sunrise in Brisbane Water National Park, Australia Brisbane Water National Park sunrise.jpg
Sunrise in Brisbane Water National Park, Australia
A daytime sky with white clouds Sky with puffy clouds.JPG
A daytime sky with white clouds

Daytime or day as observed on Earth is the period of the day during which a given location experiences natural illumination from direct sunlight. Daytime occurs when the Sun appears above the local horizon, that is, anywhere on the globe's hemisphere facing the Sun. In direct sunlight the movement of the sun can be recorded and observed using a sundial that casts a shadow that slowly moves during the day. Other planets and natural satellites that rotate relative to a luminous primary body, such as a local star, also experience daytime, but this article primarily discusses daytime on Earth.

Contents

Very broadly, most humans tend to be awake during some of the daytime period at their location, and asleep during some of the night period.

Characteristics

Approximately half of Earth is illuminated at any time by the Sun. [1]

Daytime length variations with latitude and seasons

Day length as a function of latitude and the day of the year. Latitude 40deg N (approximately New York City, Madrid and Beijing) is highlighted as an example. Hours of daylight vs latitude vs day of year cmglee.svg
Day length as a function of latitude and the day of the year. Latitude 40° N (approximately New York City, Madrid and Beijing) is highlighted as an example.
A plot of hours of daylight as a function of the date for changing latitudes. This plot was created using the simple sunrise equation, approximating the sun as a single point and does not take into account effects caused by the atmosphere or the diameter of the sun.
Earth daylight on the June solstice Earth-lighting-summer-solstice EN.png
Earth daylight on the June solstice
Earth daylight on the December solstice Earth-lighting-winter-solstice EN.png
Earth daylight on the December solstice

At the Equator

In the tropics

Around the poles

At middle latitudes

An approximation to the monthly change can be obtained from the rule of twelfths. [2]

Variations in solar noon

See also

References

  1. ↑ "Climate and Earth's Energy Budget". earthobservatory.nasa.gov. 2009-01-14. Retrieved 2025-07-09.
  2. ↑ McAdam, Marcus (14 November 2019). "The Rule of Twelfths". Mc2Photography.com. Retrieved 2021-03-11. The same Rule of Twelfths can be applied to the duration of the days.
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