Journal entry 3
- Analyse why red sunsets can sometimes be more impressive when there is more dust or pollution in the air than usual.
When there is a high concentration of particles in the atmosphere that are slightly larger than air molecules (like smoke, dust, and pollutants), shorter and intermediate wavelengths of light (violet, blue and yellow) are scattered away. Therefore, only the longer wavelengths (orange and red) reach the observer’s eyes, giving the sun a orange-red appearance.
- 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. Sometimes the colours will reach our eyes after refracting snd undergoing total internal reflection. A primary rainbow is a band in the sky with red at the top and blue at the bottom. Sometimes a less intense secondary rainbow can be seen above a primary one. Light reahces our eyes from a secondary rainbow after two internal reflections inside each rindrop. This has the effect of reversing the colours so the bottom band is red.
