Linked from
The 13 pages that link to Potential evapotranspiration, each with the reason it gives.
DesertRelated: Comparing it with rainfall helps classify dry climates.
Desert climateRelated: Comparing it with precipitation helps quantify climatic water deficit.
Aridity indexRelated: It represents the atmospheric demand commonly compared with precipitation.
AridificationRelated: Rising atmospheric demand can intensify drying even without less rainfall.
DrylandsRelated: It helps explain why limited rainfall may not meet local atmospheric water demand.
Desert (geography)Related: Comparing it with precipitation helps quantify climatic aridity.