Exploration of Natural Mysteries

Author: Li Shiji
Publisher:
Publish Date: 2006-06-01
Features: The lake that commands the wind and rain is mentioned in the classical Chinese literary masterpiece Water Margin. The legendary figure Gongsun Sheng could summon wind and rain. Now, in Nujiang Prefecture, Yunnan, the mysterious Nujiang Grand Canyon is home to an extraordinary ethnic group: the Lisu people. They can walk on swords and through flames, and possess a mysterious skill: summoning wind and rain. Is this true? Is such an extraordinary thing real?
Legends say that many years ago, a person who went to gather herbs ventured deep into Gaoligong Mountain to search for medicinal plants. With a single knife, they cleared a path and walked for a whole day before reaching the edge of a lake. At this lake, the herb gatherer was astonished to discover that they suddenly possessed a mysterious power. When they shouted loudly at the lake, it began to rain. This happened every time they tried. The discovery convinced them that they had the ability to summon wind and rain.
Later, other Lisu people who came to the lake and shouted would see clouds and mist gather, followed by rain. Thus, the locals named this mysterious lake "Listening Lake," meaning a lake that obeys commands.
Gaoligong Mountain winds through the western part of Yunnan, a mountain range spanning five latitude zones that preserves the only complete transition zone on Earth from humid tropical forests to temperate forests. As altitude changes, the vegetation also varies significantly. At lower altitudes, primitive alpine bamboo groves grow, covered in damp green moss. At higher altitudes, legendary alpine rhododendrons thrive.
Scientists have unraveled the mystery of summoning wind and rain. We know that ordinary rain requires three conditions: rising air currents, condensation nuclei, and sufficient water vapor. The rain we commonly see forms in this way: First, a cloud filled with water vapor moves over, then encounters an air current, causing it to move continuously. Inside the cloud, water vapor collides with dust-like condensation nuclei in the cold upper atmosphere, forming tiny ice crystals. These crystals collide and grow until the cloud can no longer hold them, at which point they fall as liquid water droplets, forming rain.
Artificial rainmaking utilizes the principle of ice crystal condensation. Under cloud cover, dry ice or silver iodide (a cold cloud catalyst) is scattered into the upper atmosphere to accelerate water vapor condensation and increase the number of ice crystals in the clouds, thereby triggering rainfall.
In the Gaoligong Mountain region of Yunnan, the air is moist, and the mountains are shrouded in clouds year-round, satisfying one of the conditions for rain: sufficient water vapor. But why does shouting at Listening Lake also cause rain? Could sound play the role of silver iodide?
Scientific evidence shows that when a sound source emits sound, it causes vibrations in the surrounding air, which are known as sound waves. Sound waves can disturb the air, creating collisions between air currents. At Listening Lake, the sound people make disturbs the relatively stable air, creating rising air currents that accelerate cloud movement, thus triggering rainfall.
Furthermore, due to its location in a low-latitude, high-altitude mountainous area, the region is perpetually shrouded in clouds and abundant in rainfall. Its environment is clean and simple, maintaining a fragile balance, with localized meteorological conditions often in a state of instability—on the verge of rain or no rain. Such conditions are easily affected by sound waves, whereas other areas are not in this state.
What is a critical state? For example, a full cup of water, though full, has not yet overflowed—that is a critical state. If we add just one more drop of water or gently shake the cup, the water will spill. The rain at Listening Lake works on this principle. Due to saturated water vapor, surrounded by mountains, and with no other influences, the lake maintains a stable state. Once disturbed, it changes. When the accumulation of small changes reaches a certain point, it leads to a qualitative change. Thus, the loud shouts by people at the lake can affect air currents, forming scattered rainfall. The shouts are the final drop.
Because Listening Lake is located deep in the mountains, surrounded by high peaks, this environment amplifies sound. Within the encircling mountains, people's shouts are magnified to a certain intensity, disturbing the air and causing collisions between air currents over the lake, forming raindrops. This is the secret of how Listening Lake summons wind and rain. P2-3