[1] Earth's rotation causes surface temperature fluctuations throughout the day and night, as well as weather changes throughout the year.
[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.
[5] 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.