The reading passage contends that cloud seeding is very useful when it comes to reduce hail. On the other hand, the lecturer brings up several points that contradict this argument.
First of all, according to the lecturer, the result from lab experiments is not reliable. This is because laboratory is controlled while net environment is dynamic. For example, the lecturer mentioned that there is a high chance that the chemical composition can also reduce the precipitation, which brings about the disaster of the farming area that need rain. This casts doubt on the reading, which states that hail can be controlled by using chemical compounds.
In addition, the speaker argues that although cloud seeding can be very effective in large cities that have a high level of air pollution, the effectness would not be applied to the area with less air pollution. This refutes the reading passage's assertion that cloud seeding has already been successfully experienced in Beijing to control the weather.
The final point made by the lecturer is that there is a possibility that other factors led to reduce hail. For example, the record showed that the amount of hail was reduced all over the nations at the same time, so natural weather variation might be the cause of this situation, not because of cloud seeding. This counters the writer's claim that cloud seeding have played a significant role in controllig hail. |