Knewton RC

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Knewton RC

by kaulnikhil » Fri May 28, 2010 1:41 am
Since the 1960s, the United States has operated two separate operational polar-orbiting meteorological satellite systems. These satellites obtain environmental data that are processed to provide graphical weather images and specialized weather products, and that are the predominant input to numerical weather prediction models-all used by weather forecasters, the military, and the public. Polar satellites also provide data used to monitor environmental phenomena, such as ozone depletion and drought conditions, as well as data sets that are used by researchers for a variety of studies, such as climate monitoring.

Unlike geostationary satellites, which maintain a fixed position above the earth, polar-orbiting satellites constantly circle the earth in an almost north-south orbit, providing global coverage of conditions that affect the weather and climate. Each satellite makes about 14 orbits a day. As the earth rotates beneath it, each satellite views the entire earth's surface twice a day. Today, there are two operational polar-orbiting satellites and two operational defense satellites that are positioned so that they can observe the earth in early morning, mid-morning, and early afternoon polar orbits. Together, they ensure that for any region of the earth, the data provided to users are generally no more than 6 hours old.

Polar satellites gather a broad range of data that are transformed into a variety of products for many different uses. When first received, satellite data are considered raw data. To make them usable, the processing centers format the data so that they are time-sequenced and include earth location and calibration information. After formatting, these data are called raw data records. The centers further process these raw data records into data sets, called sensor data records and temperature data records. These data records are then used to derive weather products called environmental data records (EDR). EDRs range from atmospheric products detailing cloud coverage, temperature, humidity, and ozone distribution; to land surface products showing snow cover, vegetation, and land use; to ocean products depicting sea surface temperatures, sea ice, and wave height; to characterizations of the space environment. Combinations of these data records (raw, sensor, temperature, and environmental data records) are also used to derive more sophisticated products, including outputs from numerical weather models and assessments of climate trends.


Based on the information in the passage, which of the following can be inferred?

(A) There is much more data being collected from stationary satellites than from polar-orbiting satellites at any given moment.
(B) The United States has pictures of every spot on Earth every 6 hours, going back to the 1960s.
(C) The loss of the polar-oribiting satellites would have devastating effects on a variety of data-driven industries and organizations.
(D) The satellites run by the Department of Defense are armed and able to attack any spot on the surface of the earth.
(E) Weather-prediction has become far more accurate since the advent of polar-orbiting satellites in the 1960s.


[spoiler]Can someone please explain why C is correct . I know in case you go by POE we can reach C. However my question is regarding the word devastating in option C. We can be sure that loss of the polar-oribiting satellites would have some effects on a variety of data-driven industries. However passage no where states that these effects would be devastating . We dont know whether data-driven industries can find other sources of data. Also we dont know whether polar-orbiting satellites are the only one providing data.. How can ve classify the effect as devastating ??? Somehow I find the word devastating as Extreme to use in the context[/spoiler]

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by adi_800 » Fri May 28, 2010 8:56 am
Can u let me know how you eliminated B??

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by kaulnikhil » Fri May 28, 2010 9:06 am
adi_800 wrote:Can u let me know how you eliminated B??
Read the second para carefully
Today, there are two operational polar-orbiting satellites and two operational defense satellites that are positioned so that they can observe the earth in early morning, mid-morning, and early afternoon polar orbits. Together, they ensure that for any region of the earth, the data provided to users are generally no more than 6 hours old

Passage says Today we have two operational polar-orbiting satellites and two operational defense satellites, and these two in turn help us to ensure that for any region of the earth, the data provided to users are generally no more than 6 hours old.

The passage no where mentions that two operational defense satellites have been in operation since 1960
Last edited by kaulnikhil on Fri May 28, 2010 9:10 am, edited 2 times in total.

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by student22 » Fri May 28, 2010 9:07 am
"and that are the predominant input to numerical weather prediction models-all used by weather forecasters, the military, and the public"

Predominant is your key word here. It means the main input. Basically, it's implying that without that data, the models would be incomplete.


B you can eliminate because it is too extreme. The US has pictures of every spot, every 6 hours going back to 1960? That means that not one of those pictures got lost or corrupted in that time. Also look at this line: "generally no more than 6 hours old". That means that each picture could be a little bit more or less than 6 hours.

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by Milos » Fri May 28, 2010 10:06 am
This is inferrence question. Answer must be inferred therefore. If all these important industries are based on these satelite collected information, than it can properly be inferred that they will suffer, if satelites fail to provide them further. Word devastating is little boosted, even in this case, but it is general difficulty with the GMAT...

Also, all other choices are not supported by the passage, and can't be inferred. There is no evidence that US intentionally monitors the entire world and each part of it, every 6 hours, but rather that data are collected generally ...

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