© Linda Åslund 1 particles
At a glance
Sunlight travelling through the atmosphere is scattered by gases and
During the Day
Sunlight is a mix of different coloured light. We can see these colours if we shine sunlight through a prism or if we look at the reflective side of a CD.
As sunlight travels through the atmosphere, it is scattered by gases and particles. Different colours of light are scattered by different amounts.
Blue light is scattered far more than red light.
Sunlight is travelling over our head through the atmosphere
Blue light is scattered more than any other colour so we see more blue light
During Sunrise and
Sunset
Sunlight is travelling through the atmosphere towards us
The sun is low in the sky so blue light is scattered away from us leaving more red light
The sky looks red
During the day, the sun is high in the sky and a lot of sunlight is travelling through the atmosphere far above the ground.
Red light travelling through the high atmosphere is not scattered very much and continues on through the atmosphere. However, blue light is scattered in every direction.
This means a lot of blue light reaches the ground causing the sky to look blue.
During the sunrise and sunset, the sun is low in the sky and a lot of sunlight is travelling through the atmosphere close to the ground.
As before, the blue light is scattered far more than the red light. Since the sun is now far lower in the sky, by the time the light reaches us, the blue light has been scattered so that very little remains. The red light has not been scattered as much and so the sky looks red.
Alex Brown, 2012
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