“Improbable extremes” of meteorological elements, presented here, can guide designers, manufacturers and purchasers to instruments that will be capable of measuring and recording physically possible, although highly improbable, extremes. Air temperature (T), especially a few inches above the ground, conceivably could range from −140F to 160F; dewpoint can vary from 90F down to a lowermost improbable extreme given by the relation ½T – 80. In chinook winds, temperature and dewpoint can change as rapidly as 25 deg per min. Rainfall in t minutes could amount to 2t½ inches. Wind speeds should be recordable up to 250 mph and pressures near sea level from 750 to 1060 mb, to permit measurements in hurricanes and tornadoes, where pressure might change 15 mb per sec. Atmospheric sounding devices must be able to measure temperatures and humidities within the same ranges, winds up to 300 mph, and pressure as low as 0.1 (6+log P std) of Standard Atmosphere pressure up to 133 km.

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1 Now Professor of Climatology, San Fernando Valley State College, Northridge, Calif., and Research Scientist, Geophysics Laboratory Lockheed-California Co., Burbank, Calif.