The atmospheric pressure, P, is the pressure exerted by the
weight of the earth's atmosphere.
Usage
cal_atmosphericPressure(elevation)
Value
A vector for atmospheric pressure (Kpa)
Arguments
elevation
elevation above sea level (m)
Details
Assuming 20°C for a standard atmosphere. Evaporation at high altitudes
is promoted due to low atmospheric pressure as expressed in thepsychrometric
constant. The effect is, however, small and in the calculation procedures,
the average value for a location is sufficient.
References
Allen, R. G., Pereira, L. S., Raes, D., & Smith, M.
FAO Irrigation and drainage paper No. 56. Rome: Food and Agriculture
Organization of the United Nations, 1998.