Tables 444 and 445 -389 



TABLE 444(a). — Ultra- Violet Transparency Atmospheric Components 



I = Io io- aJ , d in cm 0°C, 760 mm 



Air at sea-level (Washington), 400 m practically no absorption X > .3/n; < .28m about 

 that due to molecular scattering. Air transmission reduced by 1/100: 22 km at .28m; 5 at 25m; 

 0.57 at .22m; 20 km at .205M. (Dawson, Granath, Hulburt, Phys. Rev., 33, 1073, 1929.) 



(b). — Atmospheric Transparency for Ultra-Violet 



(Zenithsun, Fabry, Buisson, C. R. 175, 156, 1922; Astrophys. Journ., 54, 297, 1921; joined to Abbot's, Annals 

 Astrophys. Obs. Smithsonian Inst., 2, 112, 1908, via Forsythe-Christison, Gen. Elec. Rev., 662, 1929.) 



Wave length, m 29 .30 .31 .32 .33 .34 .35 .37 .39 .41 .43 .45 



% transmitted o .9 9. 20. 27. 33. 38. 46. 51. 56. 60. 64. 



TABLE 445.— Penetration Ultra-Violet Light into Sea Water 



(Hulburt, 1928.) 



The transparency of sea water declines rapidly with decreasing wave length (\) in the 

 u. v., becoming quite small below 3000 A. X 3400 to 3000 A, CaS0 4 gives % the absorption, 

 H 2 yi\ 3000 to 2500 A, MgCl 2 , CaS0 4 , H 2 each about }/$. I = I io- ax , x in cm. 



m/i 254 266 280 303 313 366 436 546 578 6i2m^i 



distilled water a 030 .021 .015 .005 .002 .001 .00005 .00015 .00028 .0010 



tap water " 045 .032 .020 .007 .003 .001 



sea water " 067 .057 .039 .017 .009 .0013 .00010 .00015 .0003 .0010 



Smithsonian Tables 



