Hail—pieces of ice that form and fall from clouds instead of snow or rain—has always been a problem for farmers in some areas of the United States. Hail pellets can fall with great force and destroy crops in the field. Over the last few decades, a method of reducing hail, called “cloud seeding,” has been tried. In cloud seeding, the chemical silver iodide is sprayed on storm clouds from an airplane. This makes the clouds produce harmless rain or snow instead of hail. Several pieces of evidence suggest that cloud seeding has been effective in protecting crops from hail.
Laboratory experiments
Experiments in the laboratory support the idea that cloud seeding is effective. Hail usually forms in water vapor that is close to the freezing point. However, when experimenters added silver iodide to cold water vapor in the laboratory, they often observed light snow forming instead of hail pellets.
Evidence from Asia
There is evidence about the effectiveness of cloud seeding from several countries around the world. In some Asian countries, for example, cloud seeding has been successfully used to control precipitation in urban areas. These positive results suggest that cloud seeding should also be effective in protecting fields and farms in the United States.
Local studies
A few local studies also support the value of cloud seeding. One study conducted in a farming region in the central United States, for example, directly monitored crop damage due to hail. The study found that in an area where cloud seeding was used there was reduced hail damage compared to previous years.
Now listen to part of a lecture on the topic you just read about.
It’s not clear that cloud seeding is all that effective and there are reasons to question each of the arguments you just read.
First, it may be true that under laboratory conditions, silver iodide creates snow instead of hail. However, in real life, silver iodide can actually prevent any precipitation at all from forming in the clouds—snow, rain, or hail. This is a bad thing, because if you seed all the clouds in areas where it doesn’t rain very often, you run the risk of causing a drought. In this case the crops simply get damaged for a different reason—lack of water.
Second, it’s not clear that the positive results with cloud seeding in Asia can be repeated in the United States. The reason is that cloud seeding in Asia was tried in urban areas—in cities. And cities tend to have a high level of air pollution—from car traffic, industry, etc. Surprisingly, pollution particles can create favorable conditions for cloud seeding, because they interact with clouds and the seeding chemicals. Such favorable conditions for cloud seeding may not occur in an unpolluted area. This means that the cloud seeding method that works in polluted cities may not work in unpolluted farming regions in the United States.
Third, the local study mentioned in the passage isn’t very convincing either. That’s because the study found that hail damage decreased not just in the area where the cloud seeding actually took place, but also in many of the neighboring areas to the east, south, and north of that area. So, the fact that the whole region was experiencing a reduced number of hailstorms that particular year makes it more likely that this was a result of natural variation in local weather and had nothing to do with cloud seeding.
There is a heated discuss on the effectiveness of "cloud seeding". The author in the reading passage gives three evidence which suggest cloud seeding has been effective in protecting crops from hail, while the professor, in the lecture, states that the effectiveness of "cloud seeding" is not clear by contradicting all these clues respectively.
First, the author asserts that cloud seeding is effective in the laboratory experiment, but the professor stresses that cloud seeding does work under laboratory conditions. however, it might prevent all kinds of precipitation in the real world, including snow, rain, and hail, which will be harmful to these areas that are not rain very much and then cause drought. Crops would be destoried due to lack of water instead of hail.
Second, although the reading passage suggests that cloud seeding has been successfully used in some Asian cities, the professor points out that cloud seeding might not be repeated in the United States, because Asian urban areas have air pollution and the chemicals in the pollution might work with cloud seeding. Therefore, cloud seeding might not work in the unpolluted area, like the farms in the United States.
Third, despite the claim in the reading passage that local studies supports the value of cloud seeding, the professor emphasizes that in the local studies cloud seeding is not only effective in the experiment area, but also adjacent areas, which means this effectiveness might be caused by the local weather in the particular year rather than cloud seeding. The professor doubts that there is nothing to do with the cloud seeding.
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Grammar and spelling errors:
Line 5, column 174, Rule ID: UPPERCASE_SENTENCE_START
Message: This sentence does not start with an uppercase letter
Suggestion: However
... does work under laboratory conditions. however, it might prevent all kinds of precipit...
^^^^^^^
Line 9, column 114, Rule ID: WHITESPACE_RULE
Message: Possible typo: you repeated a whitespace
Suggestion:
... successfully used in some Asian cities, the professor points out that cloud seed...
^^
Transition Words or Phrases used:
also, but, first, however, second, so, then, therefore, third, while
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 12.0 10.4613686534 115% => OK
Auxiliary verbs: 7.0 5.04856512141 139% => OK
Conjunction : 5.0 7.30242825607 68% => OK
Relative clauses : 12.0 12.0772626932 99% => OK
Pronoun: 13.0 22.412803532 58% => OK
Preposition: 33.0 30.3222958057 109% => OK
Nominalization: 6.0 5.01324503311 120% => OK
Performance on vocabulary words:
No of characters: 1395.0 1373.03311258 102% => OK
No of words: 263.0 270.72406181 97% => OK
Chars per words: 5.30418250951 5.08290768461 104% => OK
Fourth root words length: 4.02706775958 4.04702891845 100% => OK
Word Length SD: 2.72112146307 2.5805825403 105% => OK
Unique words: 137.0 145.348785872 94% => More unique words wanted.
Unique words percentage: 0.520912547529 0.540411800872 96% => OK
syllable_count: 405.0 419.366225166 97% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 1.0 3.25607064018 31% => OK
Article: 5.0 8.23620309051 61% => OK
Subordination: 3.0 1.25165562914 240% => Less adverbial clause wanted.
Conjunction: 3.0 1.51434878587 198% => OK
Preposition: 3.0 2.5761589404 116% => OK
Performance on sentences:
How many sentences: 9.0 13.0662251656 69% => Need more sentences. Double check the format of sentences, make sure there is a space between two sentences, or have enough periods. And also check the lengths of sentences, maybe they are too long.
Sentence length: 29.0 21.2450331126 137% => The Avg. Sentence Length is relatively long.
Sentence length SD: 107.330227698 49.2860985944 218% => The lengths of sentences changed so frequently.
Chars per sentence: 155.0 110.228320801 141% => OK
Words per sentence: 29.2222222222 21.698381199 135% => OK
Discourse Markers: 7.55555555556 7.06452816374 107% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 2.0 4.19205298013 48% => OK
Sentences with positive sentiment : 5.0 4.33554083885 115% => OK
Sentences with negative sentiment : 3.0 4.45695364238 67% => OK
Sentences with neutral sentiment: 1.0 4.27373068433 23% => More facts, knowledge or examples wanted.
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.16351065378 0.272083759551 60% => OK
Sentence topic coherence: 0.0827000394376 0.0996497079465 83% => OK
Sentence topic coherence SD: 0.0359271808762 0.0662205650399 54% => OK
Paragraph topic coherence: 0.107135199898 0.162205337803 66% => OK
Paragraph topic coherence SD: 0.0337634879423 0.0443174109184 76% => OK
Essay readability:
automated_readability_index: 18.1 13.3589403974 135% => OK
flesch_reading_ease: 50.5 53.8541721854 94% => OK
smog_index: 8.8 5.55761589404 158% => OK
flesch_kincaid_grade: 13.4 11.0289183223 121% => OK
coleman_liau_index: 14.05 12.2367328918 115% => OK
dale_chall_readability_score: 8.56 8.42419426049 102% => OK
difficult_words: 58.0 63.6247240618 91% => OK
linsear_write_formula: 15.0 10.7273730684 140% => OK
gunning_fog: 13.6 10.498013245 130% => OK
text_standard: 14.0 11.2008830022 125% => OK
What are above readability scores?
---------------------
Rates: 85.0 out of 100
Scores by essay e-grader: 25.5 Out of 30
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Note: the e-grader does NOT examine the meaning of words and ideas. VIP users will receive further evaluations by advanced module of e-grader and human graders.