JULY, 192 1 



BUL LETIN No . 391. 



Meteorological Observations 



AT THK 



MASSACHUSETTS 



AGRICULTURAL EXPERIMENT 



STATION. 



Latitude, 42° 23' 48.5" N. Longitude 72* 31' 10" \V. 



Height of barometer above ground, ^i ft. Aboi'e sea level, ^/j.j ft. 

 Height oj Wind histniments J2 ft. 21m e used, y^thMer. 



MONTHLY SUMMARY. 



Pressuie. In inches. 

 Maximum reduced to freezing, 29.92, 24.th, S a 

 Minimum reduced to freezing, 29.37, 31th, 2 P 

 Reduced maximum reading . 30.21. 2}th, 8 A 

 Reduced minimum reading, 29.63, 31th, 2 p 



Mean semi-daily reduced . 29.977 



Monthly range 0.56 



Air Temperaiure. In Degrees Fahr. 



Highest 93-5- 3d, 4 P 



Lowest 54-5. 23th, 5 A 



Mean hourly 73-4 



Mean of means of max. and min 74.7 



Mean sensible (wet bulb) 68.6 



Monthly range 39.0 



Highest mean daily 80.6. 8th 



Lowest mean daily 61.8, ist 



Mean maximum 84.4 



Mean minimum 64.9 



Mean daily range 19.5 



Greatest daily range 33.5 23d 



Least daily range 6.5,1st 



Hnmidity. 



Mean dew point 66.6 



Mean force of vapor 798 



Mean relative humidity 83.6 



Precipitation. In inches. 



Total precipitation, in inches 6.00 



Number of days on which .01 inch or more 



rain fell i 



•Temperature in ground shelter. 

 •'Reduced to freezing and sea-level. 



Wind. 



Total movement 2421 m 



Greatest daily movement 196m, 28th 



Least daily movement 13111 4th 



.Mean daily movement 78m 



Mean hourly velolsity 3.3™ 



Maximum pressure per square foot. 4.5 lbs= 



30m per hour,i4th,4P,S.S.\V.,i9th9P,S.SW. 

 .Maximum velocity for 5 minutes, i6ni per 



hour, 2Sth,4P, S. S.W. 

 Prevailing direction. South. 



Summary. 



South Southwest 32 per cent 



.South 23 " " 



North Northeast 10 " " 



Other directions 35 " " 



Weather. 



Mean cloudiness observed .... 66 per cent 

 Total cloudiness recorded by the Sun 



Thermometer . . 177 hours = 38 per cent. 



Number of clear days 5 



Number of fair days 24 



Number of cloudy days 2 



Bright Sunshine. 



Number hours recorded, 285, = 62per cent. 

 Rain, 1st. 2d, 9th, loth. 14th, 15th, 19th, 20th, 



2ith, 2Stli, 29th, 30th, 31st. 

 Thunder and Litihtninii, 5th, Sth, 9th, 



i5tli, 19th, 20th, 28th, 29th, 3ot)i. 31st. 

 Gales, None 



