Het klimaat en de verdamping van een meer in Centraal Irak

After describing the continental subtropical climate of central Iraq, Wartena assembled other meteorological observations necessary to estimate evaporation from a lake and irrigation project.

Usual formulae correlating total global radiation with duration of sunshine gave an overestimate with clear sky, an underestimate with cloud cover. A new relationship was derived which gave better results.

A critical discussion of the energy balance of an evaporation pan clearly showed that 'pan factors' could not be constants but depended on weather conditions and time of year. Kohler's theory yielded inaccurate results. Especially in and regions, to assume a constant ratio between 'potential' and actual evaporation may lead to considerable error but a 'class A' pan satisfactorily indicated irrigation requirements. The 'Piche' evaporimeter was not satisfactory.

To estimate evaporation from the projected storage lake, its surface temperatures were calculated by using elementary meteorological quantities. The method was in reasonable agreement with actual values on the existing Lake of Tiberias. The evaporation from fictitious lakes 10 and 50 metres deep was calculated to be different.

Qualitative influences of wind, humidity and temperature of the atmosphere on evaporation were discussed.

Yearly evaporation from the two lakes was estimated at 2500 mm.