What kind of weather conditions must be available for artificial rainfall during drought?

1, what meteorological conditions must artificial rainfall meet in drought?

If there is rain, there must be clouds first, and if there are clouds, there may not be rain. There are several conditions to produce rainfall: the first is the water vapor condition. The second condition is that there must be upward movement, which is equivalent to the machining process. Because the upward movement brings water vapor to high altitude and condenses to form clouds, it can produce precipitation, so the upward movement is essential. The third condition is an appropriate amount of condensation nuclei, because the condensation of water vapor needs an attachment, and water vapor cannot condense effectively without condensation nuclei. If there are not enough ice crystals in this cloud in nature, because the water droplets in the cloud are very small and can be suspended in the air for a long time without falling, then there is only cloud without rain. At this time, if silver iodide particles are sown in this cloud, many ice crystals can be produced, and the water on the water droplets in the cloud can be quickly transformed into these artificial ice crystals through evaporation and condensation, so that the ice crystals will grow rapidly and produce snowfall. If the ground temperature is high, the snow will collide and merge into water droplets while melting, and eventually become rain. This is artificial rainfall and precipitation.

2. The implementation of artificial rainfall often scatters dry ice into the sky. What is the function of dry ice?

Dry ice is solid carbon dioxide. Usually under the condition of pressurized cooling, carbon dioxide gas will become a colorless liquid, and then it will become a snowflake-like solid after the temperature is lowered. It will be made into dry ice after compression. From the appearance, dry ice is indeed similar to ordinary ice and has the same shape as ice. Under a standard atmospheric pressure, dry ice will not melt immediately after being heated, but will directly turn into gas and disappear at -78.5℃, unlike ice that will leave traces of water after melting, so it is named "dry ice" because of its unique personality, which determines that it is a better refrigerant than ice. When dry ice is gasified, the temperature of the surrounding air layer and cloud layer drops, causing water droplets to condense, and the condensed water droplets and ice crystals increase rapidly, eventually forming rainfall.