BULLETIN No. 393. 



SEPTEMBER, 192 1 



Meteorological Observations 



AT THE 



MASSACHUSETTS 



AGRICULTURAL EXPERIMENT 



STATION. 



Latitude, 42° 23' 48.5" N. Longitude 72' 31' 10" W. 



Height of barometer above ground,' ^ I ft. Above sea level, 2JJ.§ ft. 

 Height of Wind Instruments J2 ft. 7'ime used, "jijthMer. 



MONTHLY SUMMARY. 



Pressure. In inches. I 



Maximum reduced to freezing, jo.04, 20th, 12 p 

 Minimum reduced to freezing, 29.26, 30th, 3 p 

 Reduced maximum reading . 30.33 20th, 12 p 

 Reduced minimum reading, 29.54, 30th, 3 p 



Mean semi-daily reduced 30.026 



Monthly range 0.79 



Air Temperature. In Degrees Fahr. 



Highest 92.0, 2d, 1:30 P 



Lowest 36.0, 27d, 7 a 



Mean hourly 6;. 6 



Mean of means of max. and min 66.6 



Mean sensible (wet bulb) 59.4 



Monthly range 56-° 



Highest mean daily 76.(5. 3d 



Lowest mean daily S4-5. 27d 



Mean maximum 79.1 



Mean minimum 54° 



Mean daily range 25.1 



Greatest daily range 390 9th 



Least daily range 10.5, 12th 



Huniidiiy. 



Mean dew point 56.4 



Mean force of vapor 597 



Mean relative humidity 79.5 



Precipitation. In inches. 



Total precipitation, in inches i.<S4 



Number of days on which .01 inch or more 

 rain fell 11 



•Temperature in ground shelter. 

 •'Reduced to freezing and sea-level. 



Wind. 



Total movement 3568 m 



Greatest daily movement .... 282m, iSth 



Least daily movement 42m, 24th 



Mean daily movement 119m 



Mean hourly velocity 5.oni 



Maximum pressure per square foot, 8.5 lbs = 



41m per hour, 30th, 4 p, S.S.W. 

 Maximum velocity for 5 minutes, 30m per 



hour, 30th, 4 p, S.S.W. 

 Prevailing direction. South Southwest. 



Summary. 



South Southwest 23 per cent 



South 20 " " 



Southwest 13 " " 



Northwest '3 " " 



Other directions 31 " " 



Weather. 



Mean cloudiness observed .... 39 per cent 

 Total cloudiness recorded by the Sun 



Thermometer . . 122 hours = 33 per cent. 



Number of clear days 14 



Number of fair days 10 



Number of cloudy days 6 



Bright Sunshine. 



Number hours recorded, 251, = 67 per cent. 

 Rain, 3d, 6th, 7th. Sth, loth, nth, 12th, 17th, 



2ISt, 22d, 25th, 29th, 30th. 



Thunder and Liiihtninti. 'oth, 30th. 

 Gales, 40m, i8th, W.N.W.; 41m, 30th, 

 S.S.W. 



