Why do leaves turn yellow in autumn?

In autumn and winter, leaves lack sunlight, and the amount of chlorophyll synthesized in leaves is less than the amount of chlorophyll decomposed, thus revealing the colors of other pigments in plants, thus showing colors such as yellow and red.

With the gradual aging of leaves, chlorophyll decomposition in leaves is reduced, the green color of leaves is getting lighter and lighter, and other pigments contained in leaves are highlighted, among which the pigment reflecting yellow light is called lutein. The new leaves contain 8 times as much chlorophyll as lutein.

In spring and summer, yellow is hidden by green, so users can't see it. With the aging of leaves, although all the pigments contained in the leaves will be decomposed, the decomposition speed of lutein is slow, so the leaves gradually turn yellow.

temperature

Beginning of autumn doesn't mean that the hot summer will be over. beginning of autumn is still in the heat period, and the heat will not come out until the second solar term in autumn, and the weather is still very hot in early autumn.

The so-called "heat is in three volts", according to the calculation method of "three volts", beginning of autumn is often still in the "three volts" period until the summer heat, so the weather is still very hot in early autumn, and it will generally cool after the Millennium solar terms. The watershed of summer heat is in autumn, not at the turn of summer and autumn. The climate in autumn is divided into two stages, the early autumn is sultry, and the climate tends to be dry and cool after the Mid-Autumn Festival.