MARYLAND GEOLOGICAL SURVEY 



257 



May to September is practically free from injurious frosts, while the 

 period of safe plant growth may be extended to six months by adding 

 the last two weeks of April and the first two weeks of October. The 

 mean daily range in temperature, i. e. the difference between the 

 highest and the lowest recorded temperature from day to day during 

 the year is about 18°, and varies from about 21° in August to about 

 14° in January. The greatest daily range may vary from 43°, as 

 in August of 1900, to 29°, as in January, 18*97. The following 

 figures are based upon Professor Galbreath's record at Darlington, 

 Harford county: 



Greatest daily range.. . . 

 Average daily range . . . . 



PI 



1-3 



© 



c3 



< 



>> 



s3 

 3 



© 

 a 

 a 



>> 

 a 



Hi 



6c 

 < 



+3 



P. 



© 



o 

 O 



> 

 o 



6 



© 



37 



29 



36 



34 



38 



39 



34 



36 



43 



32 



41 



37 



14 



17 



17 



20 



20 



20 



18 



21 



19 



19 



16 



16 



43 

 18 



Rainfall. 



Precipitation in Cecil county is abundant and under normal condi- 

 tions is quite evenly distributed throughout the year. This is charac- 

 teristic of the Atlantic Coast states. The average annual amount, 

 including rainfall and melted snow and all forms of precipitation, is 

 48 inches. The following figures show the amount of fall in each 

 month expressed in inches and hundredths of an inch, and as a per- 

 centage of the total fall for the year : 





§ 



l~5 



© 

 ft 





p 

 < 



>> 



© 

 a 



a 



1-5 



>> 

 a 



1-5 



to 



< 



© 



+3 



o 



O 



> 

 o 



6 



© 

 P 



© 



Normal precipitation. . 



Percentage of total ) 



fall for the year. . J 



3.09 

 6 



3.65 



8 



4.27 

 9 



3.73 

 8 



4.29 

 9 



3.92 



8 



4.33 



9 



5.74 

 12 



4.01 

 9 



3.91 

 8 



3.97 



8 



3.00 

 6 



47.85 

 100 



The monthly amounts vary from three inches in January and Decem- 

 ber, the months of least precipitation, to nearly six inches in August, 

 the month of greatest rainfall. These figures may vary greatly from 

 month to month in any given year, but long periods of excessively 



dry weather are rare. Precipitation is most uniform in amount in 

 17 



