diurnal cycle

(名) 日内周期

This is another name for daily cycle. For a given location on the Earth, daily cycles in meteorological variables such as temperature, relative humidity, precipitation, wind speed, and direction are all due to the Earth's rotation (resulting in insolation differences in space and time). These daily cycles follow the insolation cycle. They are most pronounced at mid latitudes and in the tropics and least pronounced (or missing) near the poles at the time of the solstices.