Downloaded from https://www.everyspec.com (b) Storage and transit conditions. Design criteria are: four continuous hours with an induced air temperature above 140 ° F (60 ° C) with relative humidity less than 8 percent; an air temperature extreme of 145 ° F (63 ° C) for not more than 2 hours without benefit of solar radiation and with negligible wind (table 2-6). c. Basic cold daily cycle. (1) Location. Basic cold conditions are found only in the Northern Hemisphere south of the coldest areas and on high latitude coasts (e.g., the southern coast of Alaska) where maritime effects prevent occurrence of very low temperatures.
Small areas of basic cold weather conditions may be found at high elevations in lower latitudes. (2) Temperature, humidity, solar radiation. (a) Operational conditions. Design conditions are: five continuous hours with an ambient air temperature of −25 ° F (−31 ° C); a minimum ground surface temperature of −35 ° F (−37 ° C); windspeed less than 16 fps (5 mps); negligible solar radiation (horizontal surface); and humidity tending toward saturation (table 2-7). Saturation is the result of the extremely low temperatures. The absolute humidity and vapor pressure are very low when these temperatures prevail.
Although not typical, windspeeds greater than 16 fps (5 mps) may be associated with temperatures of −25 ° F (−31 ° C). 15 AR 70–38 • 15 September 1979