314 PHYSIOGRAPHY 



and the greater amount of moisture on such coasts, affect both 

 plant and animal life. These effects go beyond the mere facts of 

 life and death of the animals and plants, and even beyond the ques- 

 tion of their thrift. It affects the quality of their seeds, tubers, etc. 

 For example, wheat grown in marine climate has less nutrition than 

 wheat grown in a continental climate. Potatoes grown in the arid 

 West, where the necessary (but no unnecessary) water is supplied 

 by irrigation, are more valuable for food than those grown in moister 

 climates. 



Continental climates. In contrast with marine climates, con- 

 tinental climates have greater annual and daily ranges of tempera- 

 ture. In high latitudes the skies are clearer, and the winters colder; 

 in low latitudes the winters are warmer than over the sea. The 

 humidity is less, the rainfall is less, and the rain less frequent in 

 the interiors of the continents than over the sea; but the amount 

 and distribution of rain is influenced by topography, winds, etc. 

 The air over continents is drier and dustier than that over the 

 sea. 



A desert climate is an extreme sort of continental climate. 

 Here the daily range of temperature is great. Winds are high by 

 day, and the air dusty, often so dusty as to make travel difficult. 

 The nights are calmer and cooler. The dryness is hostile to plants, 

 and therefore to animals. 



The littoral (coastal) climate on the windward side of the conti- 

 nent is very like the oceanic climate of the same latitude. In the 

 zones of westerly winds, therefore, west coasts have oceanic cli- 

 mates, and east coasts have continental climates. In the zone of 

 trade-winds the east coasts have oceanic climates. 



The climate of the littoral zones is sometimes influenced by 

 monsoon winds. So important are these winds that it is proper 

 to speak of a monsoon climate. Monsoons are generally on shore 

 in summer, and so give summer rains if the lands are high. 



Mountain and plateau climates differ from other continental 

 climates because of (1) the greater insolation and radiation which 

 go with increase of altitude, (2) the less absolute humidity, (3) the 

 lower temperature, and (4) the greater frequency of precipitation, 

 especially in mountains, up to certain altitudes. 



