TPO 36 integrated writing skill

According to the reading passage, author lists three evidence to suggest that cloud seeding has been effective in protecting crops from hail in United States farms. However, in the listening section, lecturer stated that arguments in the passage are not so clear and convincing, also she pointed out other competing theories.
At first, the writer argues that experiments in the laboratory support the idea that cloud seeding is effective, while, the speaker admits that in real life silver iodide prevents whole precipitations such as snow and rain, so, it probably increase the risk of drought in the united states farming lands.
Second, the essay assumes that in some countries, specifically in Asian countries, cloud seeding has been successfully used to control precipitation in urban areas. In contrast, lecturer comes up with the theory that in cities with high level of pollution such as Asian cities are more favorable conditions for seeding clouds than cities with low-level of pollution such as United States cities and farm land, thus it will work better in Asian cities.
Finally, the writer supposes that based on one study in farming region in the central United States, cloud seeding used there was reduced hail damage compared to previous years, although speaker holds opposite ideas because she claims that method affected not only farming region in the central united stated, but also whole north, west, and east. Therefore, cloud seeding results in natural variation and there is nothing to do with that.