What causes the leafs in fall to change colour? (warm, days, places)

[Winter-40c]

What causes the leafs in Fall to change colour,
Do warmer places stay greener longer?

[dxiweodwo]

A combination of cooler temps, shorter days, and drier weather.

Yes, warmer places stay more green longer than colder areas.

[Zoisite]

Originally Posted by Winter-40c

What causes the leafs in Fall to change colour,
Do warmer places stay greener longer?

WikiAnswers - Why do leaves change colour in autumn

Inside the leaf there are millions of tiny discs filled with a green pigment called chlorophyll. These green 'packages' are used to trap sunlight which is used as an energy source to produce glucose (a type of sugar) in a process called photosynthesis.


There are other packages that are coloured in yellow (xanthrophyll) and some in orange (carotene), which are used in other processes in the leaf.

During the summer (in the presence of sunlight and plenty of water photosynthesis can take place) and the green packages are very active, so they hide away (or mask) the yellow and orange ones.

As fall approaches the weather grows colder and the hours of sunshine shrink as well. The trees 'realise' that winter is approaching and so they begin to prepare for it. Layers of cells grow over the tubes that carry water and glucose closing them up and making photosynthesis impossible (which requires water and sunlight).


The green chlorophyll starts to break down and disappear, and so the colours of the other 'packages' can be seen, the yellow xanthrophyll and the orange carotene. As the tubes that carry glucose are trapped as well, sugar remains in the leaves, which with time (due to sunshine and cold) give the leaves a red or purple colour. As the leaves no longer have water and glucose flowing around, they slowly die, turning into brown (chlorophyll dies first, then xanthrophyll and carotene).

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