Actual Vapour Pressure (September)

Actual vapour pressure is the variable expressing atmospheric moisture content through the partial pressure exerted by the water vapour present in the atmosphere.

The monthly uncorrected vapour pressure, ed, at any given location in South Africa was subsequently held constant for that entire month and derivatives of ed, such as daily maximum and minimum relative humidity or daily vapour pressure deficit which depend on ratios of uncorrected actual to saturated vapour pressure, were then computed using daily maximum/minimum temperatures as inputs to daily saturated vapour pressure calculations, which were in turn used with that location's monthly uncorrected actual vapour pressure.

实际水汽压（Actual vapour pressure）是通过大气中水汽所产生的分压强来表征大气水汽含量的物理量。南非任意给定地点的逐月未订正水汽压ed在整月内保持恒定；随后以逐日最高、最低气温作为输入计算逐日饱和水汽压，再结合该地点的逐月未订正实际水汽压，推求出ed的各类衍生量——包括依赖于未订正实际水汽压与饱和水汽压比值的逐日最高、最低相对湿度，以及逐日水汽压亏缺。