Diurnal cycle
Pattern with a period of one day
From Wikipedia, the free encyclopedia
A diurnal cycle (or diel cycle) is any pattern that recurs every 24 hours as a result of one full rotation of the planet Earth around its axis.[1] Earth's rotation causes surface temperature fluctuations throughout the day and night, as well as weather changes throughout the year. The diurnal cycle depends mainly on incoming solar radiation.[2]
Climate and atmosphere
In climatology, the diurnal cycle is one of the most basic forms of climate patterns, including variations in diurnal temperature and rainfall.[1] Diurnal cycles may be approximately sinusoidal or include components of a truncated sinusoid (due to the Sun's rising and setting) and thermal relaxation (Newton cooling) at night.[1] The diurnal cycle also has a great impact on carbon dioxide levels in the atmosphere, due to processes such as photosynthesis and cellular respiration.[3]
Biological effects
Diurnal cycles of light and temperature can result in similar cycles in biological processes, such as photosynthesis in plants[3] and clinical depression in humans.[4] Plant responses to environmental cycles may even induce indirect cycles in rhizosphere microbial activities, including nitrogen fixation.[5]
Semi-diurnal cycle
A semi-diurnal cycle refers to a pattern that occurs about every twelve hours or about twice a day. Often these can be related to lunar tides, in which case the interval is closer to 12 hours and 25 minutes.
See also
- Chronotype
- Circadian rhythm
- Diel vertical migration
- Diurnality
- Diurnal climate
