Out on the savanna, it has been shown that environmental conditions follow a pretty regular diurnal cycle. Around evening a strong temperature inversion usually forms and doesn't dissipate until dawn. The greatest calling areas are achieved during the formation and dissolution of the nightly inversion, especially with cloudless and relatively undisturbed weather. Under such conditions it is possible for an elephant to have a calling range of 300 km2. During the day, without the help of an inversion and with factors such as heavy sun and low wind speeds often coming into play, calling area size is drastically reduced, ranging from a couple dozen to 150 km2.