Cloud Seeding Can Aid Precipitation in Three Ways. Static mode Seeding GMAT Reading Comprehension

Reading Passage Question

Cloud seeding can aid precipitation in three ways. Static mode seeding adds silver iodide or dry ice crystals to cold clouds, causing supercooled liquid water droplets to freeze. The ice embryos that are formed can, if conditions are favorable, grow into snowflakes that fall to the ground as either snow or rain, depending on surface temperatures. (Cold cloud seeding can actually take place in warm weather, since the upper portions of cumulus clouds are cold enough for the supercooling to take place.) In dynamic seeding, a larger number of crystals are added. The resulting freezing releases heat, thereby increasing the size and longevity of the cloud. In the third method, hygroscopic seeding, clouds are seeded with salt crystals by airplanes from above, or artillery or rockets from below. These crystals introduce condensation nuclei that can increase the formation of water droplets within the cloud. This type of seeding can be effective in continental clouds, but not maritime clouds.

Concern has been expressed that seeding will “steal” rain from surrounding areas. However, seeding does not produce enough precipitation for this to be a significant factor. There is also evidence that when cumuliform clouds are present, the atmosphere continually replenishes its moisture, and that seeding can even increase precipitation in areas surrounding the target area.

The real concern is simply that seeding has not yet been shown to be effective. Cloud seeding depends on the existence of clouds, and even when they are present, some clouds cannot be seeded. Furthermore, even the proper type of cloud is only useful early in its formation, perhaps for just a few minutes. If the timing is off, the cloud can be destroyed by the process. Even if the seeding is successful, there is no guarantee that a change in the wind won’t cause rain to fall in an unintended region. Furthermore, testing for effectiveness is difficult and expensive. The normal controls of scientific experimentation are problematic when one can never know for sure whether an unseeded cloud would have produced rain.

Cloud seeding, if it ever proves to be dependably effective, will be a boon, not only to farmers, but also to hydroelectric power facilities, ski areas, and many other commercial and non-commercial interests. The difficulties of making this a reality are, however, substantial, and in some cases, insurmountable.

‘Cloud seeding can aid precipitation in three ways. Static mode seeding’’ is a GMAT reading comprehension passage with answers. Candidates need a strong knowledge of English GMAT reading comprehension.

This GMAT Reading Comprehension consists of 7 comprehension questions. The GMAT Reading Comprehension questions are designed for the purpose of testing candidates’ abilities in understanding, analysing, and applying information or concepts. Candidates can actively prepare with the help of GMAT Reading Comprehension Practice Questions.

Solutions and Explanations

1) Which of the following most accurately mimics the process of cloud seeding, as it is described in the passage above?

A) Making snow at a ski area by pumping water through pipes into snow guns, so that snow pack is increased along trails.
B) Fertilizing fruit trees in an orchard, so that they produce more fruit and do so more reliably.
C) Raising interest rates in a country, so that growth and inflation slow down to a sustainable rate.
D) Creating underwater aquaculture farms, so that mussels and oysters can flourish in places they would not naturally.
E) Constructing desalination plants, so that unusable salt water can be transformed into usable fresh water.

2) Which of the following would the author most likely regard as an accurate description of the prospects for successful cloud seeding?

A) Moderately encouraging
B) Vastly underrated
C) Inherently limited
D) Virtually non-existent
E) Impossible to gauge

3) In cloud seeding, which one of the following is mentioned as a factor in determining the form of precipitation that hits the ground?

A) The temperature in the upper portions of the clouds that are seeded
B) Whether silver iodide or dry ice crystals are used to seed the clouds
C) The number of crystals that are added to the clouds
D) The temperature at the surface below the cloud seeding
E) The type of cloud that is seeded

4) The author of the passage is primarily concerned with

A) providing an overview of the mechanics and difficulties of cloud seeding
B) arguing for a more realistic approach to cloud seeding
C) giving a brief history of cloud seeding
D) comparing the methods used to seed clouds
E) acknowledging that cloud seeding is unlikely to be very useful in the future

5) According to the passage, cloud seeding can increase the size of a cloud by

A) creating water droplets through the introduction of condensation nuclei.
B) causing supercooling to take place in the upper portion of cumulus clouds.
C) carefully targeting continental clouds at the right stage in their development.
D) using a larger number of ice crystals than is used in static mode seeding.
E) using salt crystals to release heat that expands cloud particles.

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