The region's climate has been dry since the Tertiary. The area around Licancabur is dominated by year-round high pressure caused by the South Pacific High, giving it a very sunny climate. Because of the lack of moisture, solar radiation energy is dissipated primarily by wind. In the Llano de Chajnantor area, wind generally reaches its maximum strength during the day. Its prevailing direction is from the west, except in summer when winds are more variable. Because of the area's tropical location (where the ozone layer is thinner) and high altitude, it receives a large amount of ultraviolet radiation. The world's highest level of ultraviolet radiation was reported from Licancabur, although the high irradiation might have caused measurement artifacts.