* Simple: The squirrel is a diurnal animal, active during the day.
* Descriptive: The rainforest's vibrant ecosystem thrives on the diurnal cycles of sunlight and rain.
* Contrasting: While owls are nocturnal, hawks are diurnal predators.
* Figurative: The city's energy shifted with a diurnal rhythm, bustling during the day and calming down at night.
* Formal: The diurnal patterns of animal activity are fascinating to researchers.
Remember, "diurnal" refers to something that happens or is active during the day.