BULLETIN No. 389. 



MAY, 192 1 



Meteorological Observations 



AT THE 



MASSACHUSETTS 



AGKICULTUIUL EXPERIMENT 



STATION. 



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



Hei^^ht of barometer aboTe ground, ^t ft. Above sea level, 2yj.^ ft. 

 Height oj Wind Instruments y2ft,_ Time used, y^t/iMer. 



MONTHLY SUMMARY. 



Pressure. In inches. 

 Maximum reduced to freezing, 30.12, 20th, 7 a 

 Minimum reduced to freezing, 29.41, 9th, 11 a 

 Reduced ma.ximum reading . 30.42, 20th, 7 A 

 Reduced minimum reading, 29.70, 9th, 11 .\ 



Mean semi-daily reduced 30.010 



Monthly range 0.72 



In Degrees Fahr. 



89.0, 2ISt, 3:30 P 



*Air Temperature. 



Highest 



22i, 3 P. 



Lowest 33.0, 12th, 5 A 



Mean hourly 58-9 



Mean of means of max. and min 59.0 



Mean sensible (wet bulb) 52.2 



Monthly range 56-° 



Highest mean daily 76.2. 22d 



Lowest mean daily 46.1, 25th 



Mean maximum 71.0 



Mean minimum 47.0 



Mean daily range 24.0 



Greatest daily range 37.0, 8th, 21st 



Least daily range 5.0, 5th 



Humidity. 



Mean dew point 50.2 



Mean force of vapor 507 



Mean relative humidity 75.2 



Precipitation. In inches. 



Total precipitation, in inches 4 56 



Number of days on which .01 inch or more 



rain fell 9 



•Temperature in ground shelter. 

 ••Reduced to freezing and sea-level. 



Mind. 



Total movement 4400 m 



Greatest daily movement 2S6m, 5th 



Least daily movement 62m 27th 



Mean daily movement 142m 



Mean hourly velocity 5.9 m 



Maximum pressure per square foot, 6.5 lbs = 



36m per hour, 9th, 3 p, N. W. 

 Maximum velocity for 5 minutes, 24m per 



hour, 9th, 3 p, N.W. 

 Prevailing direction, Southwest. 

 Summary. 



West 13 per cent 



Northeast 10 " " 



-South 19 " " 



South Southwest 10 " " 



Other directions 48 " " 



Weather. 



Mean cloudiness observed .... 36 jier cent 

 Total cloudiness recorded by the Sun 



Thermometer . . 148 hours = 33 per cent. 



Number of clear days 16 



Number of fair days 10 



Number of cloudy days 5 



Briijht Sunshine. 



Number hours recorded, 305, = 67 per cent. 

 Rain, ist, 5th. 6th, 13th, Mtli, 15th, 16th, 22d, 



23d, 25th, 29th. 

 Thunder and Liiihtninii, 22d, 29th. 

 Frosts, I2th. 

 Gales. 36ni. 9th., N.W. 



