The Bailey system is based on climate , and is divided into four domains ( Polar , Humid Temperate , Dry , and Humid Tropical ) , with further divisions based on other climate characteristics ( subarctic , warm temperate , hot temperate , and subtropical , marine and continental , lowland and mountain ) . The Bailey system is based on climate and is divided into seven domains ( Polar , Humid Temperate , Dry , Human , and Humid Tropical ) , with further divisions based on other climate characteristics ( subarctic , warm temperate , hot temperate , and subtropical ; marine and continental ; lowland and mountain ) .