2,391 research outputs found
Growing-Degree Units For Selected Agricultural Locations In Alaska
Paper copies in Archives, Acc #:2013-0059It is well known that the rate at which a plant grows is influenced by air temperature. The
problem is to define this relationship in a quantitative manner so that the information can be applied to agricultural problems. In places where growth of a particular crop is limited by the length of the growing season, an evaluation of the "heat-units" available is particularly important. Many heat-unit systems have evolved over the years, with certain advantages claimed for each. In crop production, heat unit systems are used to estimate the time required for a crop to go from one stage of development to another, usually from planting to harvest. Each heat-unit system produces a particular set of values, the values being determined by the relationship between temperature and growth that is assumed in the calculations. This paper lists heat-units available in six areas in Alaska, all having agricultural potential. The system used measures temperature in "growing-degree units" and is described in detail. Recent comparative studies of growing season and growing degree days leads to the conclusion that the temperature records taken at Big Delta may have been favorably affected by the nearness of the weather recording station to an extensive coated runway. The "flywheel" effect of this large heat sink appear to have reduced the occurrence of 32°F. night temperatures in both the spring and fall, making the growing degree accumulation unrealistic.Introduction and general comments -- Description of Stations -- Results and discussion -- Summary -- References -- Appendix -- Figures: Fig. 1 Average weekly growing degree units for Matanuska Experiment Station; Big Delta; University Experiment Station, Fairbanks; Homer; Kasilof; and Kodiak. Fig. 2 Seasonal growing degree unites (May 15 to 1st 30°F or lower temperature in fall) which will be equaled or exceeded for varying probability levels at Big Delta, Matanuska Experiment Station and University Experiment Station, Fairbanks. Fig. 3 Seasonal growing degree units (May 15 to 1st 30°F or lower temperature in fall) which will be equaled or exceeded for varying probability levels ta Homer, Kasilof, and Kodiak. Tables: Table 1 Comparison of growing-degree units (GDU) for Clearwater and Big Delta for the period 1965-70. Table 2 Highest, lowest and average weekly GDU values for Big Delta, and values which will be equaled or exceeded for given probabilities. Table 3 Highest, lowest and average weekly GDU values for Homer and values which will be equaled or exceeded for given probabilities. Table 4 Highest, lowest and average weekly GDU values for Kasilof and values which will be equaled or exceeded for given probabilities. Table 5 Highest, lowest and average weekly GDU values for Kodiak and values which will be equaled or exceeded for given probabilities. Highest, lowest and average weekly GDU values for the Matanuska Experiment Station, and values which will be equaled or exceeded for given probabilities. Table 7 Highest, lowest and average weekly GDU values for the University Experiment Station, Fairbanks and values which will be equaled or exceeded for given
probabilities at 6 Alaska locations. Table 8 Highest, lowest and average monthly GDU values and values which will be equaled or exceeded for given probabilities at 6 Alaska locations. Table 9 Highest, lowest and average seasonal GDU values and values which will be equaled or exceeded for given probabilities for the period May 15 to date of first 30°F or lower temperature in the fall at 6 Alaska locations
You Can Figure Your Spring Freeze Hazard
If you feel like gambling on the date of the last spring freeze, here is a quick way to find out whether or not the odds are in your favor
How Much Corn This Fall?
There\u27s less corn in Iowa corncribs this summer than for a good many years. So there\u27s more than the usual concern over what this season\u27s crop will be
You Can Figure Your Fall Freeze Hazard
When will the first bad freeze hit next fall? To many Iowa farmers, that\u27s an important question. An exact answer could help in doing a better job of farm planning
Comparative study of turbulence models in predicting hypersonic inlet flows
A numerical study was conducted to analyze the performance of different turbulence models when applied to the hypersonic NASA P8 inlet. Computational results from the PARC2D code, which solves the full two-dimensional Reynolds-averaged Navier-Stokes equation, were compared with experimental data. The zero-equation models considered for the study were the Baldwin-Lomax model, the Thomas model, and a combination of the Baldwin-Lomax and Thomas models; the two-equation models considered were the Chien model, the Speziale model (both low Reynolds number), and the Launder and Spalding model (high Reynolds number). The Thomas model performed best among the zero-equation models, and predicted good pressure distributions. The Chien and Speziale models compared very well with the experimental data, and performed better than the Thomas model near the walls
What Does the Weatherman Mean?
The terms your weather forecaster uses have specific meanings. His forecast will be more meaningful to you if you know just what the terms mean
Soil Moisture Situation 1957
Your bank account of soil moisture can\u27t be overdrawn - nature won\u27t advance the funds. Your account for 1957 crops depends on the current balance plus any amount of moisture added, absorbed and held
Precipitation probabilities in the North Central States
Cover title.Includes bibliographical references
The climate of Iowa: the occurrence of freezing temperatures in spring and fall
No type of agriculture can be establish ed profitably in a region unless the risk of loss to that type o f agriculture from unfavorable weather conditions is more than balanced by the profits of other times. The farmer should know the risk involved in raising a given crop at a given time. One of these weather risks is minimum temperatures. Minimum temperatures are important at all times of the year, but at certain times, the occurrence of especially critical temperatures is of extreme importance. A killing freeze is often a factor limiting production. Killing freezes may occur in the spring to damage perennial crops that start growth early in the season, o r annual plants that get an early start and are then injured by a late spring freeze . Killing freezes may also occur in the fall and terminate the growing season. In either case , severe damage can be caused and heavy losses incurred . Injury may also occur to perennial crop s from sub zero winter temperatures, but that type of freezing weather will not be covered in this report.https://lib.dr.iastate.edu/specialreports/1005/thumbnail.jp
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