562 



TEMPERATURE IN RESPECT TO ALTITUDE. 



Insular and coast climates are more equable, from the effect of the sea 

 in preventing the atmosphere from being much heated during the day, 

 and much cooled during night. In the interior of vast continents the 

 extremes of temperature are often great Winds have a powerful effect 

 on climate. In China, the north-east monsoon brings great cold in 

 February. The state of a country as regards forests, has a decided effect 

 on the temperature. In different quarters, the nature of the exposure, 

 also, whether to the east or west, north or south, and the intervention 

 of elevated ranges of mountains, materially affect the temperature. 



1137. Temperature, in its hypsometrical (ttyo?, altitude, and ftsr^on 

 measure,) relation, or as regards its altitudinal range, requires to be 

 considered. In ascending into the atmosphere, a decrease of tempera- 

 ture is observed, which varies in its amount at different stages of ascent. 

 The following table shows the temperature at different heights in the 

 equatorial and temperate zones: 



Height 

 in feet. 



Equat. Zone. 

 Lat. 10 



81.50F. 



3,197 71 .24 



6,394 64 .40 



9,591 57 .54 



12.789 44 .60 



15,985 37 .70 



Mean. 



Temp. Zone. 

 Lat. 45 47 



53.60 F. 

 41 .00 

 31 .64 

 23 .36 



Taking an average, it may be said that there is a fall of 1 in the 

 thermometer for every 340 feet of ascent. Prof. Forbes states that 

 549.5 feet of ascent give a difference of 1 of the thermometer in the 

 boiling point of water. The elevation at which constant frost takes 

 place is called the snow-line or line of perpetual congelation. Its 

 limit does not exactly correspond with the height at which the temper- 

 ature is equal to 32 F. The following table gives the height of the 

 snow-line (in feet) at different latitudes : 



T D , Height of 



M? Snow Line. 



15,207 



5 15,095 



10 14,764 



15 14,220 



20 13,278 



25 12,557 



30 11,484 



35 10.287 



40 9,001 



45 7,671 



T at Height of 



^ at - Snow Line. 



50 6,334 



55 5,034 



60 3,818 



65 2,722 



70 1,778 



75 1.016 



80 457 



85 117 



90 .. 



The decrease of temperature on lofty mountains regulates, in a great 

 measure, the nature of the plants which grow at different heights. The 

 same changes take place as have been shown to occur in proceeding 



