diurnal variation; daily variation; diel cycle
Scientific term for changes that occur over a 24-hour cycle, often used in meteorology, biology, and environmental science.
I showed the diurnal variation of temperature on a graph.
In this lake, the diel cycle of dissolved oxygen is large.
Compound of 日 (にち, 'day') and 変化 (へんか, 'change, variation'). The reading follows standard on'yomi.