Green snow is snow colored by a growth of green algae.
More specifically, the green coloration in snow is usually caused by the presence of cold-tolerant green algae, most commonly Chlamydomonas nivalis. While often referred to as "snow algae," it's technically a type of green algae. This algae thrives in freezing temperatures and uses sunlight for photosynthesis, just like plants. The algae can also contain a red pigment (carotenoid) for protection from UV radiation, causing a pink or red hue – often called "watermelon snow" or "blood snow." When green algae dominates, the snow appears green.
This phenomenon is most often observed in alpine and polar regions during the spring and summer months when sunlight is more abundant, and the snow begins to melt. Patches of green snow can appear on glaciers, snowfields, and mountaintops.
Here's a breakdown of the key aspects:
- Cause: Primarily Chlamydomonas nivalis algae.
- Location: Alpine and polar regions.
- Season: Spring and summer.
- Appearance: Snow with a distinct green tint or patches.
- Impact: Can darken the snow, leading to increased absorption of sunlight and accelerated melting.
While visually striking, the presence of green snow algae can contribute to glacial and snowpack melt, potentially impacting water resources and ecosystems.
