150 PRINCIPLES OF STRATIGRAPHY 



III. Evaporation in 24 hours with varying humidity and a tem- 

 perature of the air of 20° C. 



Relative humidity 81-85 % i • 23 



Relative humidity 71-75 % i . 44 



Relative humidity 61-65 % 2 . 06 



Relative humidity 51-55 % 2.66 



Relative humidity 41-45 % 2 . 97 



Experiments by Schott have given the following results in con- 

 centration of normal sea water through evaporation at a tempera- 

 ture of the air ranging around 25° C. and an average velocity of the 

 wind of 7.5 meters per second. The measurements were made on 

 the Atlantic from the 5th to the 8th of September, 1892, at 8 o'clock 

 each morning, on 10 liters of sea water, in a vessel giving 600 

 square centimeters surface, and fully exposed to the wind. 



Salinity Height of water 



Date (8 A. M.) permille column in cm. Volume c. c. 



Sept. 5 36.3 16.5 10.000 



Sept. 6 38.5 16.2 



Sept. 7 40.3 15.9 



Sept. 8 42.1 15 -6 9 360 



Thus in tlirce days the decrease in volume was about 6 per cent., 

 while the increase in salinity was nearly 6 permille. 



Bathymctric Variation. Besides the regional variation, there is 

 a bathymetric variation in the different water bodies. In rare cases 

 is the salinity uniform throughout (homaline) ; it is commonly vari- 

 able (lictcroJialinc). A decreasing salinity downward constitutes an 

 anoJialinc arrangement {ah) ; an increasing one is a katohaline 

 (kh) condition. A decreasing followed by an increasing salinity 

 downward constitutes a dichohaline (dJi) condition, while the re- 

 verse, an increasing followed by a decreasing salinity downward, 

 constitutes a mesohaline condition (uih), the most saline layers being 

 in the middle. (Kriimmel, 20: jj^.) These relations may be sum- 

 marized graphically as follows : 



Decreasing Increasing 



salinity salinity 



Homohaline ] 



Anohaline y 3" tr* 



Katohaline \ o^q 



Dichohaline z' ^p 



Mesohaline \ ^ <^ 



Heterohaline 



