METEOROLOGICAL OBSERVATORY 



OF THE 



Hatch Experiment Station 



MASSACHUSETTS AGRICULTURAL COLLEGE, 



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



Height of barometer above ground, 51 ft. Above sea level, zyj.^ ft. 

 Height of Wind Instruments 72 ft. 



BULLETIN No. 2 16. 



DECEMBER. 1906. 



MONTHLY SUMMARY. 



Freaattre. In inches. 



Maxunum reduced to freezing, 30.44. iqth, 9 a.; 

 Minimum reduced to freezing, . 29.16, 3d, 3 p. 

 Reducedt maximum reading, 30.77, 19th, 9 a.; 

 Keducedt minimum reading, . . 29.47, .^d, 3 p. 



Mean semi-daily reduced, 30.124 



Monthly range 1.3° 



*Air Temperature, In Degrees Fahr. 



Highest 45.5, ist, IP. 



Lowest, —3-0, 8th, 7:00 a. 



Mean hourly, 24.2 



Mean of means of max. and min 24.1 



Mean sensible (wet bulb), 21.2 



Monthly range, 48.5 



Highest mean daily 40.0,1st 



Lowest mean daily, 4.4, 8th 



Mean maximum, 3i-5 



Mean minimum, .... 16.7 



Mean daily range 14 



Greatest daily range 35.0, 7th, 



Least daily range, 3.0, 21st 



Humiditi/. 



Mean dew point, 16.5 



Mean force of vapor 135 



Mean relative humidity, 77.0 



Freelpitntion. In inches. 



Total precipitation, 4.49 



Number of days on which .01 inch or more 



rain or melted snow fell, 10 



Total snow in inches 12 



• Temperature in ground shelter. 

 t Reduced to freezing and sea-level. 



Wind. 



Total movement 5554 m. 



Greatest daily movement, 441 m.,2d 



Least daily movement, 28 m., 17th, 



Mean daily movement, 179 m. 



Mean hourly velocity, 7-5 m. 



Maximum pressure per square foot, 12.0 lbs. = 

 40 ni. per hour, ist,6 p., W.N.W. 



Maximum velocity for 5 minutes, 36 ni. per 

 hour ist, 7 P., W.N.W. 



Prevailing Direction, North, Northwest. 



Summary. 



North, 19 percent. 



North Northwest, 16 " " 



North, Northeast, 13 " " 



West 10 " " 



West, Northwest, 10 " " 



South, Southwest, 10 " " 



Other directions, 22 " " 



Weather. 



Mean cloudiness observed, . . . .66 per cent. 

 Total cloudiness recorded by the Sun Ther- 

 mometer, .... 172 hrs.=6i per cent. 



Number of clear days, 9 



Number of fair days, 6 



Number of cloudy days, 16 



Rrlght Sunshine. 



Number of hours recorded, . . iii hrs.=39# 

 R«iM, 6th, loth, 15th, 20th, 2ist, 22d, 30th, 



31st. 

 Snow, ist, 3d, 4th, 6th, 8th, 9th, 13th, 15th, 



20th, 22d, 23d, 25th, 27th, 28th. 



Dayg Sleighing 21. 



Oales,2S miles or more per hour, 49 m. ist, 

 W.N.W.; 37 m. 2d, W.N.W.; 37 m. 3d, 

 N.; 36 m. 4th. N.N W.;37m.7th, W.N.W.; 

 35 m. i8th., N.N.E.; 36 m. 24th, N. 



