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

The red sunset all depends on how bright the white light beam. If the beam is very bright, no dust or pollution will effect the powerful red sunset, but if the white light is very dark, there will be only a small red sunset, then the dust and the pollution will effect the red sunset. The other main reason is because of scattering of light.

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

Water droplets act like tiny prisms in the sky, sometimes the colour will hit our eyes after refracting an undergoing total internal reflection. Droplets higher in the sky refract red into our eyes, while green and blue go overhead. In drops lower in the sky, blue light is refracted and reflected to our eyes, but green and red light lower down, missing our eyes. The overall effect would be a primary rainbow – this is where red is at the top and blue is at the bottom. If it’s a secondary rainbow, blue would be at the top, and red would be at the bottom.