Water 47 



If, then, another pound of hot water, the same temperature 

 as the first reading, be taken and a pound of small stones at the 

 same temperature as the cold water be dropped into it, the tem- 

 perature of the mixture of the stones and hot water will be 

 changed only a little from that of the hot water. The heat used 

 to warm the cold water in the first part of the experiment must 

 have been taken from that of the hot water. The same is true of 

 the stones, but it will be noticed that the hot water did not cool 

 as much when the stones were placed in it. This shows that 

 less heat was needed to warm the pound of stones than the pound 

 of water. 



Climatic Effects of Water. Bodies of water are one of the 

 principal modifiers of climate. Water both heats and cools slowly. 

 It absorbs heat and then as gradually gives it off. During the 

 hot months the oceans and lakes become storehouses of vast 

 quantities of heat. Since water does not receive or give off heat 

 readily, large bodies of water may be exposed for a long time to 

 hot weather conditions without becoming very warm, or to cold 

 weather conditions without becoming very cold. The temperature 

 of the ocean varies only about 15 Fahrenheit during the whole 

 year. 



Land warms and cools more rapidly than water. Land be- 

 comes quite warm during the day while the sun shines and causes 

 the temperature to become higher, but since land gives off its 

 heat quickly, the temperature lowers rapidly at night. Hence, 

 while water experiences only slight and gradual changes of tem- 

 perature, land experiences great, and often sudden temperature 

 changes. It follows that inhabitants of places located near large 

 bodies of water enjoy a more uniform climate than those who 

 live in places in the same latitude far inland. 



Lake, river and sea breezes are likewise caused by the fact 

 that land raises the temperature of the atmosphere above it by 

 giving off heat, so that the warm air rises and cooler air rushes 

 from the lake, river or sea to take its place, thus causing a sea 

 breeze in the daytime. At night, when the land becomes cool 

 and reaches a temperature below that of the water, the air cools, 

 settles and flows out toward the warm water of the lake, river or 



