Even though the weather is still fairly warm in the Waikato, we all definitely get the feeling that Autumn is upon us. The trees are changing colour and starting to look pretty vibrant. But how do the leaves change colour? I have hazy recollections of science lessons at school where we learnt words like photosynthesis (where C02 + water + light is converted by the plant into sugar for the plant to "eat", and oxygen) and chlorophyll (the greening substance in the leaves, which aids the photosynthesis through light absorption). In Autumn the days become shorter, therefore there is less light and the chlorophyll withdraws from the leaf allowing the other colours to show through. These colours have been there the whole time, but because of the green chlorophyll we can't see them. Cooler climates produce even more spectacular colour, which is probably why we often see incredible Autumn photos of places like Arrowtown and Queenstown, The picture below is of the Clinton River in Southland.