Describe the two main methods of cloud seeding and evaluate how effective cloud seeding efforts have been
What will be an ideal response?
Answer: Cloud seeding involves injecting one of two materials into nonprecipitating clouds. The objective is to convert some of the supercooled droplets in a cool cloud to ice and cause precipitation by the Bergeron process.
One of the materials, dry ice (frozen carbon dioxide), promotes freezing because of its very low temperature (below ?78 °C or –108 °F). Very small shavings of dry ice can be ejected from a plane flying through the cloud. When introduced into a cloud, dry ice lowers the temperature of the droplets so that freezing can occur by homogeneous nucleation. (Recall that at temperatures below about -40 °C water droplets require no ice nuclei to freeze.) The second agent for cloud seeding, silver iodide, initiates the Bergeron process by acting as an ice nucleus at temperatures as high as -5 °C (23 °F). Silver iodide owes its effectiveness as an ice nucleus to its six-sided structure. Like dry ice, silver iodide can be introduced directly into a cloud from aircraft. The cost effectiveness of cloud seeding is widely debated. Under ideal circumstances, it can supplement water supplies somewhat. Strong theoretical reasons provide grounds to doubt the usefulness of cloud seeding.
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Using the analemma, answer the following questions:
1. Determine how much the declination of the Sun changes during the following 10-day periods.
2. Based on your calculations in problem 1, as well as your general observations of the analemma, answer the following questions:
(a) During which two times of the year (six months apart) is the declination of the Sun changing most rapidly from one day to the next? (You may name the two months of the year when declination changes most rapidly, or name the two special days of the year around which declination changes most rapidly.)
(b) During which two times (or months) of the year (six months apart) is the declination of the Sun changing most slowly?
3. Solar altitude and length of day are related to the declination of the Sun. Using the analemma and your answers for problems 1 and 2 for reference, answer the following questions:
(a) How much does the solar altitude in your city change over the following 10-day periods? (Hint: No new calculations are necessary; see your answers to problem 1.)
12/12 to 12/22: ____________ 3/20 to 3/30: ____________
(b) During which two times of the year (six months apart) does solar altitude and length of day change most rapidly from one day to the next?
(c) During which two times of the year (six months apart) does solar altitude and length of day change most slowly?
4. It is May 5 and you are somewhere in the Northern Hemisphere. If you determine that the noon Sun is 51° above your southern horizon, what is the latitude of your location?
Which of the following significantly improved air quality in the United States?
A. The elimination of chlorofluorocarbons. B. Eliminating lead in paint. C. The use of catalytic converters. D. All these statements are correct. E. None of these statements are correct.
Cratons are generally of low elevation and old in age
Indicate whether the statement is true or false
Finance is not a single industry, but a set of closely related sectors that revolve around ________
Fill in the blank(s) with correct word