Peruvian Andes: the Power of a Blue Sky

After many days of continuous, gentle rain that turns the valleys and pampas into lush green lawns, today in the Peruvian Andes from Huaraz to Cusco was the day of the clear blue skies. On such days, the wind tends to be stronger, weaving through the eucalypto trees and the tall dahlias—red, yellow, and pink in full bloom. These are warm days, with the heat welcomed to dry the wet adobe walls of the camp houses, the trails, and the laundry.

In the picture above, the water and the sky are a uniquely beautiful blue. But this isn't a warm, soothing blue—it's the icy blue of a cold morning at a high-altitude lake in the Sacred Valley. Despite the chilliness, there's something equally pleasant about that blue. Why is that?

According to the phenomenon of Rayleigh scattering, sunlight enters the Earth’s atmosphere and collides with gas molecules and particles. These collisions scatter the shorter, more energetic wavelengths of light, like blue and violet, in all directions. Our eyes are particularly sensitive to blue light, which is why we perceive the sky as a soft, calming blue.

Spending time under a blue sky can have profound effects on our emotional well-being. Studies have shown that natural environments, particularly those with clear skies and open landscapes, can help increase feelings of relaxation. Exposure to natural light and open skies has also been linked to the release of serotonin, the "feel-good" neurotransmitter. This helps explain why just a few moments spent outdoors on a clear day can lift our spirits, ease stress, and give us a renewed sense of clarity and calm.