Colours of nature (part 2)

The other major colours you see in nature are green from foliage and blue for water. The sea looks blue because it reflects the sky. Water itself is transparent. Small depths of water look transparent (like a bathfull) but if you look through enough water (like when you are underwater and can see a long way) things look blue because there are so many water molecules that they absorb most of the colours completely. The only colours that can can more than about 20 metres are blue and a bit of green - that's why things underwater seem blue-green. From land the sea looks blue because it reflects the sky. So when the sky is grey the sea looks grey.


Plants are green because they absorb all colours except green. They break up water and carbon dioxide molecules and fit them together to make oxygen and sugars. They do this using a molecule called chlorophyll. If you give a chlorophyll molecule just the right amount of energy it will give you an electron. This 'just right' energy just happens to be the same energy of a blue particle of light. You can also get an electron if you give it a red light particle. This will have a different energy to a blue light particle but it turns out that this energy is also just right to get another electron from a different part of the structure. When chlorophyll has all these electrons loose they get passed around between loads of chlorophyll molecules until eventually they hit water and carbon dioxide molecules and help them to break down and reform into sugars. So blue and red light get absorbed by chlorophyll and green gets scattered back - green particles don't have the right energy to release an electron. That's why plants are green. Not all plants use light to make food. Funghi and mushrooms decompose dead or living tissue to make food. They often grow in fields or woods where little animals die and rot or the leaves and bark from trees rot. They don't need light and are rarely green.