Why do leaves turn yellow in autumn?

Children, in a few days, it will be the first solar term in winter-beginning of winter. This means that from the lunar calendar, autumn has passed. Autumn has many characteristics. I wonder if my friends have found it? For example, in autumn, the original green leaves will turn yellow. With the autumnal equinox blowing, they will fall from the trees and float to the path, which is a beautiful scenic line. But have you ever thought about why the leaves turn yellow? It turns out that all leaves contain green chlorophyll. Trees use chlorophyll to capture light energy and store it in the form of chemicals such as sugar with the help of other substances in leaves. Besides chlorophyll, many leaves also contain other pigments, such as yellow, orange and red. Although these pigments can't carry out photosynthesis like chlorophyll, some of them can transfer the captured light energy to chlorophyll. In spring and summer, the content of chlorophyll in leaves is much richer than other pigments, so the leaves show the green color of chlorophyll, while the colors of other pigments are invisible. When autumn comes, the days get shorter and the nights get longer, which makes the trees begin to shed their leaves. Before the leaves fall, trees no longer look for samples to produce a lot of chlorophyll as in spring and summer, and the existing pigments such as chlorophyll will gradually decompose. In this way, with the gradual reduction of chlorophyll content, the colors of other pigments will gradually appear on the leaves, so the leaves will show yellow, red and other colors.