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Charles E. Robertson

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Charles E. Robertson

Abstract

Data from an optical snow-rate sensor have been compared with snowfall rates measured directly and with crystal types and degrees of riming. it is shown that the device provides a reliable measure of snowfall rate only when the crystals are unrimed. This may be characteristic of any such instrument based on this optical technique.

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Charles E. Robertson

Abstract

In a cloud seeding program, it is necessary to know what meteorological conditions are controlling the travel of artificial ice nuclei. While it is obvious that they will travel with the air currents, it is difficult to determine if the currents will travel to the desired area, and how much time is taken to transport the nuclei from the generator to the target area. Silver iodide particles were generated in a cyclic manner from ground-based generators, while continuous observations of ice nuclei were made on the surface in the target area. Observations show the surface wind velocity at the generator site to be the primary factor controlling the particle travel. However, nuclei concentrations have been observed to remain low even though the wind velocity was favorable for detection. This may be due to the silver iodide particles nucleating the cloud to form ice crystals, which do not enter the nucleus counter.

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Farn P. Parungo and Charles E. Robertson

Abstract

An experimental weather modification program using silver iodide as the cloud seeding agent is being conducted over the Park Range in northwestern Colorado. The measure of silver content in target area precipitation can be used as an aid in tracking the silver iodide plume and evaluating seeding results.

The ultramicroquantities of silver in snow samples are concentrated by a solvent-extraction technique with an organic complexing reagent, and silver content is then determined by atomic absorption spectrophotometry. This analytical method is capable of detecting silver iodide activities in seeded snow. The results obtained using this technique on Park Range target area snow samples are discussed.

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Donald A. Burrows and Charles E. Robertson

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No abstract available.

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