Nadir is employed during remote sensing of the atmosphere, as well as when an astronaut faces the Earth while performing a spacewalk. The term nadir can also be used to represent the lowest point reached by a celestial body during its apparent orbit around a given point of observation. This can be used to describe the location of the Sun, but it is only technically accurate for one latitude at a time and only possible at the low latitudes. The sun is said to be at the nadir at a location when it is at the zenith at the location's antipode
Overhead line are constant, fixed termination (FT) equipment may be used, with the wires terminated directly on structures at each end of the overhead line. The tension is generally about . This type of equipment sags on hot days and is taut on cold days. With AT the continuous length of overhead line is limited due to the change in the position of the weights with temperature as the overhead line expands and contracts. This movement is proportional to the tension length, the distance between anchors. Tension length has a maximum. For most 25 kV OHL equipment in the UK, the maximum