This spring, Huanggang City suffered a drought that has not happened in 50 years. In order to alleviate the drought, the meteorological department of this province used rockets and anti-aircraft guns for artificial precipitation enhancement. The following are First, artificial rainfall is the use of dry ice sublimation or high-altitude decomposition of silver iodide as a catalyst to form rainfall. So, it is correct.

B, artificial rainfall, water vapor in the air condenses into small ice crystals or liquefies into small water droplets. So, it is correct.

C, the implementation of artificial rainfall, must be the air contains a lot of water vapor. At this time, dry ice is thrown into the sky, which sublimates and absorbs heat, so that the temperature drops and the water vapor condenses or liquefies. So artificial rainfall is affected by the weather, so it is wrong.

D, the water vapor in the air will condense into small ice crystals, gradually become larger, fall down, and will melt when it meets the heating flow, forming rainfall. So, it is correct.

So choose C.