Journal 3

1. Analyse why red sunsets can sometimes be more impressive when there is more dust or pollution in the air than usual.

Red sunsets are caused not because of refraction of sunlight, but because of a phenomenon known as scattering in which molecules of gas and dust particles in the atmosphere alter the direction of light rays.

-Science Focus 3,Kerry Whalley,pg110

Sunsets, spectacular as they can be, are in part the result of all the pollutants we have pumped into the air.

Water, dust, and pollutants act as tiny prisms that cause the light to bend. The different particles scatter and change the light by refracting it; each color is produced by different refractory properties of the junk.

If there were no particles in the atmosphere, there would be no sunsets.

-http://wiki.answers.com/Q/Why_are_sunrises_and_sunsets_sometimes_red

Describe what happens inside water droplets to cause a rainbow and explain how you can tell whether a rainbow is a primary or secondary.

Small droplets of water behave like tiny prisms in the sky. The droplets will reach our eyes after undergoing total internal reflection. Droplets higher in the sky refract red to our eyes, while green and blue go overhead. We can tell a primary colour because a band in the sky with red at the top and blue at the bottom. And sometimes a less intensive secondary rainbow can be seen above a primary one.Light reaches our eyes from a secondary rainbow after two internal reflections inside each raindrop. This has the effect of reversing the colours so the bottom band is red.

-Science Focus 3, Kerry Whalley,pg 111

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