Precipitation is always in the form of snow at high altitudes, and rain is almost unknown. On some days, between 10 a.m. and 2 p.m., the air temperature near the ground rises sharply. Above a plain, vertical convection cells were produced. In the mountain range, the ascent of the air is made along the valleys and the slopes of the hills, which act as actual chimneys. The pressure on the summits drops considerably. This breeze (from the Valley) causes, in the afternoon, the formation of cumulus clouds. From January to April, the air is so dry in the Andes that the cumulus clouds are not produced despite the breeze from the Valley. At night the opposite occurs, and a cold breeze blows from the Cordillera over the Central Valley.Climb Aconcagua
Towards 35 ° south latitude, the high peaks and the area in which the summer is arid except for rare and brief storms is determined. Three phenomena characterize this part of the Andean Cordillera:
The omnipresence of fields of penitents above 4000 or 5000 meters, due to the prolonged dry season Aconcagua expedition
The little development of the snowfields. Glaciers are fed exclusively by refreezing and not by snow compression.
The abundance of underground glaciers is covered by carry-over material. The low humidity, the low percentages of oxygen, and the strong winds are just some of the most greatest characteristics of the climate of this hill. The leading causes of storms and those responsible for bad weather are fundamentally the humid winds expelled by the Anticyclone of the Pacific, which run towards the South and rise towards the West, colliding with the mountainous mass of the Cordillera, cooling and where its humidity becomes snow on the high peaks of the Andes. On Aconcagua, there are storms of snow and wind, and due to its geographical location, the most feared storms are electrical storms. The mountain ridges (the northwest sector and the top) are most visited by electrical sparks (lightning), making it challenging to stay and climb.
On the Aconcagua hike, strong winds blow from the West (at more than 5500 meters above sea level), which, added to the large size of the hill, form the giant and famous mushroom. This is located in the upper part of Aconcagua and can be seen from Plaza de Mulas, creating a beautiful landscape and a terrible negative forecast of strong winds and high rainfall. Approaching or entering at such times would be deadly. When coming it is advisable to leave the top of the mountain.