The Chacaltaya GAW Station (CHC) is located in the Bolivian Andes. Chacaltaya is a mountain with a horizon open to the south and west facing the Altiplano (plateau of 3800 masl). Behind CHC (towards the north and east), high peaks of the mountain range (Cordillera Real) separate it from the Amazon Basin. The climate is semi-arid, but the summit of Chacaltaya is often in the clouds. The area surrounding the CHC is stony, partly covered by snow (especially in summer) and with little fauna and vegetation.