Relative Humidity Data Analysis: Relative Humidity

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4.1.6 Relative Humidity Data Analysis
Relative humidity is the relative measure of the extent of moisture in the air to the amount required to saturate the air at the identical temperature. The relative humidity of the air is mostly contingent on temperature and rain fall. According to Shaw, 1985, relative humidity is the relative measure of the amount of moisture in the air to the amount needed to saturate the air at the same temperature ed/ea represents as a percentage. RH=(ed/ea) 100 where: - RH is relative humidity, ed is actual vapor pressure at the dew point, Td; ea is saturated vapor pressure at air temperature, Ta

As air humidity is in an instance of increasing, its ability to absorb water vapor decreases and evaporation rate slows down. For evaporation to undergo there must be a difference in humidity (Tenalem Ayenew and Tamiru Alemayehu, 2001; Fetter C.W, 1994).

Table 4.9 Relative humidity (%) stations in the study area stations Jan Feb Mar Apr May Jun Jul Aug …show more content…

In many instances a value for the potential evapotranspiration is calculated at a close by climate station on a reference surface, conventionally short grass. This value is known as the reference evapotranspiration, and can be changed to a potential evapotranspiration by multiplying with a surface coefficient. In whatever way, this particular procedure is depend on the assumption that PET is affected only by meteorological circumstances, does not take into account the effect of vegetative density and maturity. The Thornthwaite method is known to methodically underestimate PET in more arid regions and seasons. Quantifying of the potential evapotranspiration, calculated on monthly principles, is given

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