Between 24 and 25° degrees southern latitude the Andean Dry Diagonal crosses the Andes. At this latitude, half of the precipitation falls in summer and the other half in winter. The formation of this dry diagonal is an effect both of the rainshadow effect of the Andes, air subsidence within South Pacific High, and the cold Humboldt Current off the Pacific coast. This is the reason why the Atacama Desert exists. The extremely arid climate at Llullaillaco is also a consequence of these climatic effects.