According to popular belief, particularly brightly coloured leaves in autumn are a sign of a harsher winter. But is this really the case?
Leaves change colour in autumn mainly because the production of chlorophyll, the green pigment essential for photosynthesis, decreases as a result of lower light levels and temperatures. When chlorophyll disappears, other pigments, such as carotenoids (yellow, orange) and anthocyanins (red), appear, as explained by Science et Vie.
But does this have anything to do with winter? Well, not really. In reality, the bright colour of the leaves depends on several environmental factors. These include temperature, particularly during cool but not frosty nights, which promotes the production of red anthocyanins. But also sunshine, which affects the intensity of autumn colours. And finally, humidity and dryness, which can also influence the quality and duration of the colours.
In other words, brightly coloured leaves mainly reflect specific weather conditions in autumn, but do not necessarily predict the severity of the coming winter.
