The large ears of elephants aid cooling by radiating heat from blood vessels, and flapping to generate cooling air currents.
Elephants have quite large ears that help them overcome one of their biggest challenges due to their habitat: heat. They use their ears to dissipate heat for thermal regulation. They can achieve losing heat up to a decrease by 9 °C with the adaptations they evolved using their ears.
These adaptations include some evolutionary developments in traits and behaviour. The skin of their ears are relatively thin compared to other parts of their body. Therefore their blood vessels located underneath the skin of the ear are exposed to and affected by the external conditions much more. They use this unique trait in effectively cooling down their body. They spray their thin-skinned large surfaced ears with water and flap them to create cooling air currents for create evaporation which results in evaporative cooling - just like humans sweating. Their blood vessels exposed to this thermoregulatory behaviour swiftly, and the blood passing through ears are cooled by 9 °C.
Foy, S. (1983). The grand design: Form and colour in animals. BLA Publishing Limited for J.M.Dent & Sons Ltd, Aldine House, London.