aridity classmeans any of the following categories in which areas are classified according to the aridity index:
aridity indexmeans the ratio between precipitation and potential evapotranspiration;
organic soilmeans a soil either fulfilling the definition based on approved national standards, used for reporting under the United Nations Framework Convention on Climate Change (UNFCCC), or, where there are no such standards, using criteria listed in 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines (Annex 3A.5.