Dancers find exhilaration in feeling 'blue'
On a sleepless night in early spring of 2013, standing on the balcony of his New York apartment, choreographer Cheng Tsung-lung saw the sky begin to fill with a magical blue hue. For some 20 minutes, the sun was still below the horizon but the sky started to glow.
Cheng was so fascinated by the moment and the color that he went to check out how to describe it in English. Then he got to know of the "blue hour".
It refers to the period of twilight when the sun is below the horizon and the its indirect rays take on a blue cast. The effect is caused by the shorter wavelength of blue light than that of red. During the "blue hour", red light passes straight into space while blue light is scattered in the atmosphere and therefore reaches the Earth's surface.
