MARYLAND GEOLOGICAL SURVEY 177 



The effect of the proximity of the ocean and Bay on the amount of 

 precipitation in Calvert County is comparatively slight. It is true that 

 the air contains more moisture than the interior regions, but the country 

 is flat and cannot cause upward deflection of the winds and consequent 

 cooling by means of which condensation is chiefly brought about. The 

 precipitation in Calvert County is less than in counties northward on the 

 same meridian, but slightly more than in some interior counties. When 

 local storms occur in which ascending air currents are produced by 

 strictly dynamic causes, the abundance of moisture is such as to make 

 very heavy rainfalls possible over limited areas, such, for instance, as 

 occurred at Jewell, July 26 and 27, 1897, when 14.75 inches fell in less 

 than 21 hours. 



Calvert County is too far from the Appalachian mountains to be 

 directly influenced by them, though sharing with other portions of the 

 State in the protection afforded by the mountain barrier 'to the sweep 

 of cold waves from the west. At the same time the prevailing north- 

 west winds of winter must necessarily bring down to the level of the 

 Coastal Plain the colder bracing air of the nionntains, thus counteracting, 

 as before stated, the effects of neighboring water surfaces and emphasiz- 

 ing the continental character of our climate. 



Meteorological Data Available for Calvert County. 



The meteorological data available for Calvert County are unfortu- 

 nately very limited. Only two co-operative stations have ever existed in 

 the county, both of which are still in operation. Prince Fredericktown 

 was establislied February 1, 1899, by the Maryland State Weather Ser- 

 vice with Mr. Alfred Presson as observer. The instruments are private 

 property but ai'c of standard pattern, and are exposed about 2 miles 

 north-northeast of Calvert County court house, Lat. 38° 34' N., Long. 

 76° 35' W., at an elevation of about 80 feet above sea level. This series 

 of observations is very much broken and no record for an entire year 

 exists. 



The only other station in tlie county is Solomons, situated on an 

 island at the extreme southern point of the county. Under the auspices 



