Altitudinal zonation is the creation of zones to explain the different characteristic climates at different elevations. The different zones can support different vegetation, agriculture, etc. As one moves to higher elevation points one enters different altitudinal zones. The lowest zone being Terra Caliente, and the highest zone being Tierra Helado. Founded by a geographer named Humboldt. Humboldt is also credited with Environmental Lapse Rate - the measure of how many degrees temperature drops as you move to higher elevation (3.5 F every 1,000ft.).