Mooring the boat xuyi is the frosty season.

Introduction

Frostfall is one of the twenty-four solar terms and the last solar term of autumn, which means that autumn is about to end and winter is coming. As the saying goes, "Frost kills all kinds of grass", after the frost, the weather is getting cold, frost is frost, cold air is more and more frequent, the temperature difference between day and night is big, the plants gradually lose vitality, the earth is in a slump.

It is worth noting that the frost does not necessarily mean "frost". Because in meteorology, the first frost in the fall is generally referred to as the early frost or the first frost, and the last frost in the spring is called "late frost" or "final frost"; from the final frost to the first frost of the interval period, is the frost-free period.

However, the ancients did not have such advanced observation instruments and big data calculations in modern times, but just according to the experience, generally after the frost festival will be out of frost (in the northern region), so the last festival in the fall named frost, is also more accurate.

Because "frost" is a sign of cold weather and a big difference in temperature between day and night, the festival is named "Frost" to indicate "a sudden drop in temperature and a big difference in temperature between day and night". The "frost" festival reflects the weather gradually become cold climate characteristics, not that into this festival will be frost.

In fact, "frost" is not from the sky down, "frost" is the ground water due to temperature changes in the cold air condensed into. The "frost" festival has nothing to do with the "frost".

Changing Phenomena

After the frost, the earth is in a state of depression, and the leaves of most plants begin to wither. As a result of the low temperature, the chlorophyll in the leaves is damaged and takes on a carotenoid color, thus most of them begin to yellow, however, there are many species of trees that contain anthocyanins in their leaves, so they gradually turn red.

The most famous trees that turn red in autumn are maple and sumac, while others, such as yellow wood, sequoia, lacquer tree, and slack tree, all show attractive colors, so it is a great pleasure to climb up in autumn to enjoy the red leaves and see the forest in full color.

There are numerous poems about leaf-appreciation throughout history, the most famous of which is of course Du Mu's "Walking in the Mountains": "The rocky paths on the cold mountains are slanting in the distance, and there are people living in the places where the white clouds are born. The most famous of all is Du Mu's "Mountain Walk": "Far away from the cold mountains, the stone path is sloping, the white clouds have homes.