- Latitude and Elevation: The southern Andes are located at high latitudes, between approximately 35 degrees south and 55 degrees south. At these latitudes, the Earth receives less direct sunlight, resulting in lower temperatures favorable for glacier formation. Additionally, the Andes mountain range is high in elevation, with peaks reaching over 6,000 meters (19,700 feet). Higher elevations experience colder temperatures and increased precipitation, contributing to the formation and accumulation of snow and ice.
- Precipitation and Snowfall: The southern Andes receive significant amounts of precipitation, particularly in the form of snowfall. The prevailing westerly winds originating from the Pacific Ocean carry moisture-rich air masses that rise and cool as they encounter the mountains, leading to heavy precipitation on the western slopes of the Andes. This abundant snowfall becomes the primary source material for glacier formation.
- Atmospheric Circulation Patterns: The interaction between the westerly winds and the topography of the Andes creates specific atmospheric circulation patterns that influence precipitation and glacier formation. These patterns include:
- Orographic lift: As the moist air rises over the Andes, it cools and condenses, forming clouds and precipitation on the windward (western) side of the mountains.
- Rain shadow effect: On the leeward (eastern) side of the Andes, the descending air masses experience warming and drying, leading to a rain shadow effect. This results in drier conditions on the eastern slopes and reduced glacier formation compared to the western slopes.
- Temperature and Solar Radiation: The amount of solar radiation reaching the surface plays a crucial role in glacier formation and melting. The southern Andes experience variations in solar radiation due to changes in latitude and seasonal variations in the Earth's tilt. During the winter months, when solar radiation is reduced, the cooling temperatures promote glacier growth. In contrast, during the summer, increased solar radiation causes some melting and glacier retreat.
- Local Topography and Aspect: The topography of the Andes and the orientation of mountain slopes also influence where glaciers form. Valleys, cirques, and steep slopes provide suitable terrain for glacier accumulation and flow. Glaciers are more likely to develop in areas with favorable slope angles that allow for the accumulation and movement of snow and ice.
- Remnant Glaciers: Glaciers in the southern Andes are remnants of much larger ice sheets that existed during past ice ages. These glaciers survived the warming climate by retreating to higher elevations and areas with optimal conditions for their preservation.
