Colorful glow is the result of short-wave red or orange light dyeing left by a large number of air molecules scattered by sunlight through the thick atmosphere before and after sunrise and sunset. When there are many impurities in the air, such as dust and water vapor, its color is more obvious. Generally speaking, the fluctuation of atmospheric dust is small, while the change of water vapor is large, so whether the glow is significant generally reflects that the atmosphere contains a lot of water vapor. If there are clouds, the clouds will naturally be dyed into bright orange colors. Whether there are bright red rosy clouds before or after sunrise or sunset, it shows that there is a lot of water vapor in the atmosphere, but why is it the same sunrise, and the sunrise will turn bad the rainfall? Because the weather and wind direction in the northern hemisphere in spring and summer are mostly southeast winds, a large amount of water vapor that forms rainfall is basically transported from the southeast. Sunglow shows that a large amount of water vapor flows to the local area. After sunrise, the temperature rises and airflow convection accelerates, which is easy to form thunderstorm weather (convection can be understood as the fluctuation and friction of water vapor molecules, resulting in cooling, condensation and electricity). Moreover, due to China's topography and altitude, the ground airflow containing a large amount of water vapor is easy to cool down and condense raindrops to form a rain cloud system during the westward drift and altitude increase, and the possibility of rain is gradually increasing, so Sunglow is a sign that the weather will turn to rain. Then why does the bright red and golden sunset herald sunny weather? Because sunset certainly represents the same moisture as sunrise, but because it is sunset time, the temperature tends to be stable and the airflow convection decreases, so the possibility of rainfall decreases. Secondly, the appearance of the sunset glow also shows that the weather in the west of the sunset glow has cleared up or the clouds have split, and the sunlight can penetrate to form the sunset glow, indicating that the water vapor in the southeast wind is rising, evolving into the rain cloud system in the east, which has almost dried up. Therefore, the sunset glow also indicates that even if it is still raining locally, the rain clouds above it will soon be exhausted.
So why do we see the rain belt moving in the opposite direction to the southeast wind? It seems that the rain came from the west and floated from the west, which has nothing to do with the water vapor provided by the southeast coast. Nature is often mysterious, and its appearance often makes us see an illusion. Although it is a southeast wind near the ground, it is basically a westerly wind at the top of the earth (it is these two different directions that form typhoons and cyclones). Although the water vapor in the ground southeast wind rises with the increase of illumination, temperature and height, and its wind direction is northwest, the cloud system formed by the water vapor carried by the ground southeast wind is from west to east under the action of the high-altitude westerly wind, so the drifting direction of the cloud image we see is basically eastward; But why does the water vapor and rain curtain provided by the east open from west to east in turn? Because the process of water vapor forming raindrops in the east can only be formed when it drifts to the northwest and gradually releases heat and cools down, and when the altitude increases, the temperature drops and the water vapor concentration increases continuously, once rain forms in a certain area on the way to the west, it means that this area becomes a cooling area, and a large amount of water vapor accumulation and the cloud temperature drop caused by rain (air convection and raindrops drop drag caused by rain lead to the drop of cold air in the upper air, which makes the temperature of the cumulonimbus layer and the ground drop at the same time), and the temperature drop has two results:
First, a large amount of water vapor carried by the southeast wind is blocked by the cold airflow in the rainfall area, which slows down or stops the westward movement, forcing the water vapor of the southeast wind airflow to rise in situ during the compression and temperature rise of the airflow, directly increasing the local water vapor content;
Secondly, the temperature drop in the cumulonimbus layer, due to the condensation of a large number of water vapor, contributed to the rapid development of the rain cloud system from west to east, so the rain area spread from west to east like a domino dominated by cold air, and a large-scale rainfall from west to east began. The appearance of sunset shows that the rain in the west has stopped, and the water vapor content in the atmosphere has dropped greatly, so the phenomenon of cloud cooling accompanied by rainfall has disappeared, and the rain situation formed by condensed raindrops has also dissipated with the clouds, and good weather has come.