TPO 36 Integrated Writing Task

Recently the discussion of how to make clouds produce harmless rain or snow instead of hail has been under discussion. While the reading material provides evidence supporting cloud seeding method to protect crops form hail damage, the listening material casts serious doubts on them.

First of all, the author believes that experiments in laboratory has proved that adding silver iodide to cold water vapor can form light snow instead of hail. However, the speaker argues that in real life, it will prevent the precipitation including rain and snow from forming in clouds. It will cause damage to crops if no rain because they need water to survive. The negative risks might follow cloud seeding.

Secondly, the passage maintains that cloud seeding has been proven effective in some Asian urban areas and it may also be effective in protecting fields and farms in the US. Nevertheless, the listening contends that Asian countries are different because these urban areas have high air pollution created by car traffic, and industries. Cloud seeding favors these conditions but this might not be able to work in unpolluted cities farm region in America.

Finally, the author states that local studies have found reduced hail damage compared with previous year using cloud seeding by monitoring crop damage in the central US. On the other hand, the lecturer alleges that the reduction in hail damage took place not only in this area but also in other neighboring areas like Eastern, Southern, Northern areas. So the cloud seeding probably had nothing to do with this result.