Monthly Summary 



December, 1930 



Normal 1 



Extremes 



Barometer 



(Readings reduced to sea level) 



Maximum 30.64, 2nd, 3rd 



Minimum 29.38, 9th 



Mean semi-daily 29.706 



Range 1.26 



Air Temperalure 



Highest 45, 1st, 9th, 20th 



Lowest . 1, 16th 



Mean 28.1 



Monthly range 44 



Highest mean daily 39.5, 9th 



Lowest mean daily 10.5, 16th 



Mean maximum 35.3 



Mean minimum 20.9 



Greatest daily range 33, 17th 



Least daily range 4, 12th 



Precipitation 



Precipitation. In inches 1.63 



Snow, in inches 13.75 



Maximum precipitation in 24 hrs. 



.57, 26th, 27th 

 Number of days on which .01 or 



more inches of rain fell 9 



Wind (miles) 



Total movement 4,355 



Greatest daily movement 382, 2nd 



Least daily movement 28, 30th 



Mean hourly velocity 6.0 



Maximum velocity for 5 min. 32, 1st, 9th 

 (corrected to conform to 3 cup anemometer) 



Wind (direction) 



Prevailing direction nw 



North, days 4 



Northeast, days 1 



East, days 



Southeast, days 8 



South, days 1 



Southwest, days 



West, days 3 



Northwest, days 14 



Weather 



Mean relative humidity, per cent. . 72.0 



Mean cloudiness, per cent 67 



Number of clear days 10 



Number of fair days 4 



Number of cloudy days 17 



Number of hours bright sunshine 100.0 

 Percent of possible hours of bright 



sunshine 35 



Thunder and lightning 

 Frosts 



30.65 



29.25 



30.056 



1.40 



54.5 

 -2.3 

 27.3 

 56.8 



3.47 

 8.99 



9 



4,726 



6.4 

 29 



77.2 



53.4 



8 



10 



13 

 130.7 



46 



30.96, 1889 

 28.85, 1915 



1.78, 1895; 1.01, 1892 



65.5, 1908 

 -22.5, 1917 



7.77, 1901; 0.87, 1896 

 26.50, 01, 02; t, 1891 



17, 1902; 4, 1892 

 6,694, 1925; 3,239, 1918 



41, 1928 



87.1, 1919; 67.2, 1890 

 68, 1897; 39, 1919 



15, 1890; 2, 1922 



16, 1909; 4, 1889 

 19, 1911, 1922; 7, 1909, 1923 



172, 1896; 86, 1922 



No TE— The first column in the above summary gives observations made during the 

 month. The second and third columns give the averages and extremes observed from 1889 

 to 1929. 



