Why can Zhuge Liang calculate the east wind in Chibi but not the rain in the valley above?

From a novel perspective, first of all, these storylines all come from the Romance of the Three Kingdoms by Mr. Luo Guanzhong. In the Romance, Zhuge Liang has a lot of skill points, but some plots require Zhuge Liang to give way. After all, Sima Yi is the last one. winner. If Sima Yi died, the history of the Three Kingdoms would almost completely change. When writing the novel, Luo Guanzhong could not deviate from the historical facts of the ending of Cao Wei's unification of the country to write about the Three Kingdoms. Because the plot requires it, Sima Yi cannot die. This rain in the upper valley is particularly important.

From some scientific point of view: First of all, it is easier to predict the wind direction than the rain. This has been the law since ancient times. In the Battle of Chibi, it was not difficult for Zhuge Liang to borrow the southeast wind. Zhuge Liang himself had learned some meteorological observations. In addition, the wind direction along the river has certain rules. Everyone who lives by the river knows this, so it is not particularly strange that Zhuge Liang can calculate the southeast wind.

The rain in Shanggu is not only a matter of weather, but also may be caused by human factors.

Let’s take a look at the overall topography of Shangfang Valley. The place name Shangfang Valley is very descriptive. Its entrance is very narrow, its hinterland is wide, the sides are relatively high, and the middle is relatively low. Such terrain is not conducive to air flow. If there is a fire in the valley at this time, the temperature will continue to rise, and then the air close to the surface will heat up and expand, while the cold air in the upper layer and nearby will begin to sink, thus forming strong convection. There will be strong winds.

The hot air will condense into clouds when it rises and becomes cold. At this time, the large amount of smoke and dust produced by the burning firewood provided by the Shu army provided ideal condensation nuclei for the condensation of water vapor, thus accelerating the condensation of water vapor. The small water droplets in these clouds and mist collide and merge with each other, and the volume will gradually increase, eventually leading to heavy rain. This is known as convective rain.

So even if Zhuge Liang knew astronomy and astrology, he would not be able to fully understand all the modern geography knowledge.