182 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1930 



are not displaced and thus may be distinguished from true solar 

 lines. A spectrum of the impressive B group of atmospheric oxy- 

 gen is reproduced in Plate 5, Figure 1. These lines coincide in the 

 spectra of the east and west limbs while the solar lines are mutually 

 displaced. 



In the case of sun spots, it has made it possible to build up a pic- 

 ture of the motions of the surrounding vapors and to fathom the 



l.<i km. per sec. 

 i HjKa 



7^H<, 



Heigfht 



•e>,000 km 



Hg K.^ 



\ \ V^l , / / 



/ 



/ 





\ 



/. 



CHROMOSPHERE. 



\ 



\ 



S 



\ 



\ 



\ ^ \ ' fC<y4zzi\ 

 \ ^ \ ll' 1^ AU 15-20 LfeOS-AO) LEV€L OF 



Yl ^ \ I ^f<3 10 /] VELOCITY INVERSION 



\ /^ \ i^^^f^^A^ R^ER^ING. LAYER 





\ 



/ \ — ^ — ^^if^~r^ — ^ \ 



/ 



PH0Ti^6PHECE. 



FiGUKK 1. — Vertical section of a sun-spot vortex sbowing circulation of the gases at 

 different hiigbts and the lines of tlie magnetic field. To be considered iu con- 

 nection with the horizontal section of the high-level vortex photogrraphed in the 

 light from hydrogen at the height of 8,000 Ism. Plate 4. 



sun's atmosphere. When the spectra of the centerward and the 

 limbward edges of the penumbra of a sun spot suitably situated 

 between the center and limb of the sun are photographed in juxta- 

 position, it was found by Evershed that for lines of moderate 

 strength the two spectra are displaced, the one from the center edge 

 toward the violet and the one from the limb edge toward the red 

 (pi. 5, fig. 2). Interpreted as a Doppler effect, the displacement 



