It also exists for horizontal thermal advection at different altitudes. An isothermic layer, with a lapse rate of zero, may extend over several hundreds of metres. In other cases, rather than falling, temperature climbs with altitude. This is an inversion caused by a negative thermal lapse rate. Sometimes such inversions are caused by energy that has been stored near the surface during the day and rises during a cloudless night, reducing the surface temperature.
Inversions are more frequent in winter than in summer.
2.8 Scales used to measure temperature In Canada, the Celsius scale is used almost exclusively to express temperatures at the surface and aloft. On a Celsius thermometer, water freezes at 0 and boils at 100 . Figure 2-3 Temperature scales The Kelvin, or absolute, scale is more useful for scientific applications. It is divided in exactly the same way as the Celsius scale, but with zero indicating the lowest temperature theoretically obtainable.