174 



THE CLIMATE OF CALVERT COUNTY 



a region by lessening the extremes both of summer heat and winter cold, 

 especially the latter." 



Viewing more closely the relative temperatures of air and water, it 

 is found that in tropical oceans the temperature of the water is always 

 higher than the temperature of the air above it. In middle latitudes 

 the water is slightly cooler than the air during the warmest portion of 

 the day. The hourly temperature of the waters of the north Atlantic 

 Ocean about the latitude of southern Maryland are given in the follow- 

 ing table, which also shows the extent to which the air above is warmer 

 or colder than the water, and the extremely small range of both. 



TABLE I. 



Hourly Tempeeatures of the Surface Waters of the North Atlantic Ocean and 



OF THE Air Above (Hann). 



Time | 



Water 



Air 



Difference — 



Means. 



67.8 



67.3 



-0.5 



The monthly mean temperature of the surface waters of the Atlantic 

 Ocean are also generally above the mean temperature of the overlying air 

 except where cold ocean currents prevail. 



The effect of the oceans in mitigating temperatures is nowhere more 

 strikingly shown than on the west coast of Europe. England, which lies 

 on the same parallel as inhospitable Labrador, has a climate proper to a 

 latitude 20 degrees farther south. This is due, not to the higher tem- 

 perature of the Gulf stream itself, but to the modifying influence of 



- It may perhaps be well to show by a numerical calculation the amount 

 of heat given up to the air by water in cooling. The amount of heat required 

 to warm one cubic centimeter of air 1° C. is only 0.00031 calories; therefore 

 the specific heat of air is 3257 times smaller than that of water. If a surface 

 layer of water 1 centimeter thick cools one degree, the quantity of heat 

 liberated would raise the temperature of a mass of air 33 meters thick 1° C. 

 "When water freezes a large additional quantity of heat is given up to the 

 air. (Hann.) 



