What is 'Winterline', seen only in Swiss Alps and Mussoorie?
The 'Winterline', visible clearly only in Mussoorie and Swiss Alps, is formed due to a combination of atmospheric conditions. It's a distinct horizontal line that appears in sky, caused by temperature inversion and light refraction through dust particles. The result is a visible demarcation line in sky, with one area appearing lighter blue while the other takes a darker tone.