A boat heads for home as the sun sets over Lake Michigan. On the last weekend of Summer, rain showers interrupted much of the day, yet as if on queue, the sky cleared for sunset. As we watched the sun dip below the horizon for the last time this summer, I noticed the usual bands of red, yellow, and white appear on the photos I captured. Adusting the shutter speed to bring out the intense reds in the clouds, only brought out more of the bands in the sun. Just as the moon appears larger and more colorful when it's lower in the sky, the sun also appears to change at sunset. When the moon or sun is low in the sky, the light emitted from them must travel through more of the earth's atmosphere. The atmosphere is different temperatures at different levels, so the light is distorted a bit at each level, creating a mirage that changes the shape and color of the sun as it sets. That's why the solar disk is flattened and has different bands of color.
Posted by Tom Gill at Tuesday, September 23, 2014