Three types of airmasses in which tornadoes form are identified from consideration of 286 representative soundings and a median sounding for each type presented and discussed. Previously published descriptions of tornadic airmasses are identified as being of TYPE I, the most common TYPE, and some refinement is given. Two other TYPES are described and it is contended that all tornadoes and water spouts of the continental United States and adjacent waters form in airmasses that fit one of the three classifications. Finally, the weather phenomena that most commonly accompany tornadoes in each TYPE of airmass are described and related to the height of the wet-bulb freezing level above the terrain.
An optically powered sound alerter has been constructed which demonstrates the feasibility of converting optical power into sound power with good efficiency and at power levels comparable to those of present telephone ringers. The alerter has an overall optical-to-acoustic efficiency of about 35 percent at 2 mW of acoustic output power. Optical power is converted to electrical power by a 52-percent efficient pho tovoltaic detector and then into acoustical power by a 72-percent ef ficient electroacoustic tone generator which uses a piezoelectric transducer. This demonstration establishes that it is technically fea sible to deliver optically, via a fiber lightguide, sufficient power to op erate a telephone, since all other telephone signaling functions can be accomplished, in principle, with less power and within the context of dielectric lightguide technology. For conventional usage, the design of a telephone alerter must take many factors into consideration, in cluding background noise masking, frequencies not irritating to the customer, satisfactory performance for customers with impaired hearing, etc. These factors have not been addressed here.
A commercial Creusot-Loire BC-105 twin-screw expanded dry pet food extruder was operated to provide extruded moistures between 7.9% and 12.4% at constant product density. Low moisture extrusion decreased product uniformity 45% and product shape roundness by 70%. It increased air ceil size 41% and internal fissuring by 25%. After drying all samples to low moisture, the samples extruded at a low initial moisture were more fragile with 15% lower ultimate strength as measured by crushing with an Instron testing machine.
All upper-air soundings in the United States have been evaluated since January 1, 1950 and 274 selected as representative of air in which hailstones of known size formed. These soundings are summarized and several parameters which are or may be useful in forecasting are discussed. A graph is presented, which permits the translation of a forecast of air structure into one of hailstone size and two groups of forecasts are summarized to show the validity of this forecasting tool. The forecasts discussed were prepared in practical situations by meteorologists on regular forecasting duty and issued before the storms occurred. They therefore constitute a real test of the method under working conditions. Evidence is presented to show a very striking relation between the incidence of surface hail and the height of the wet bulb freezing level above the terrain. It was found that in 91.6% of the 274 representative soundings, the wet bulb freezing levels were between 5000 and 12,000 feet above the surface and the larger the reported surface hail, the greater the concentration of these levels near 8000 feet. It is emphasized that the method of hail forecasting discussed is not susceptible to machine methods, but depends on accurate prognostication of the thermodynamic structure of the air column as it changes in time and space.
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