What is a leaf fall

Leaf fall

October 10, 2011 | Dipl.-Met. Christian Herold

Two old farmer rules say: "If the leaves fall early in the garden, it is
beautiful autumn and mild winter to be expected. "and" Depends the foliage
into November, the winter will be long. "What about these
Farmer rules on?

First of all it should be explained why the trees are in autumn
lose their foliage. Trees get their energy from sunlight
Photosynthesis. To do this, they need chlorophyll, the green one
Leaf dye. Because of the lack of light and the cold, the
Photosynthesis does not take place in winter. Furthermore, lose
Deciduous trees have a lot of water over their leaves, which in winter when frozen
It is difficult to replenish soil through the roots. Therefore
Deciduous trees pull all nutrients out of the leaves in autumn.
This breaks down the green chlorophyll in the leaves. Back
remain yellow and red leaf pigments, which degrade more slowly, or
still to be built. This creates the typical bright red
and yellow coloring of the leaves, as they are currently found in nature
can be observed everywhere. Are all nutrients removed from the leaf,
a separating layer grows between the leaf stalk and the branch. Now is enough
a light gust of wind to separate the leaf from the tree.

Due to the color of the leaves or the fall of leaves, the
Phenology, among other things, the beginning of full autumn and the
Defined late autumn. The phenological seasons are adjusted
according to the developmental stages characteristic of the season
various Central European plants. The full autumn begins
when horse chestnut, oak, ash and red beech discolor their leaves. The
Late autumn begins when these tree species lose their foliage.

This process is triggered by the shorter day length
and the falling temperature. After several cool nights it will
Correspondingly, chlorophyll degrades faster. This is how they are directed
Leaf color and fall according to the prevailing weather in the
Autumn instead of the weather in the coming winter. Therefore
Even with these pawn rules, no statements can be made about the
Meet the course of the coming winter.

But what you can predict is the further development for them
new week. So the trees are at in the first half of the week
changeable and windy weather will continue to lose their leaves.
Towards the end of the week, it is likely to be partly foggy, partly
sunny high pressure weather. It can be especially in the northeast
give the country night frost.

© German Weather Service