PRO Fig1,scale
; IDL Version 4.0.1 (Win32 x86)
; Journal File for user@Microsoft Windows Host
; Working directory: C:\RSI\IDL40
; Date: Tue Nov 05 11:36:11 1996
 
psopen,'\usask\893\fig1.ps',/landscape

IF N_Elements(scale) EQ 0 THEN BEGIN
    scale=(0.05/640.)*Long(!D.Y_SIZE)
    Help,scale
    ENDIF

cx=0.15*!D.X_SIZE
re=6371.
cy=!D.Y_SIZE/2-scale*re & Help,cy

arcs,re*scale,105,75,cx,cy,/dev ; define Earth surface

; define ozone layer "boundaries" and apogee height
arcs,(re+10)*scale,105,75,cx,cy,/dev,linestyle=1
arcs,(re+40)*scale,105,75,cx,cy,/dev,linestyle=1
arcs,(re+80)*scale,105,75,cx,cy,/dev,linestyle=1

; define 1-km layer at ozone "peak"
arcs,(re+25)*scale,105,75,cx,cy,/dev,linestyle=2
arcs,(re+26)*scale,105,75,cx,cy,/dev,linestyle=2

; show radius from center of Earth to 100 km altitude
plots,[cx,cx],[cy+scale*(re-1000),cy+scale*(re+100)],/dev

; show horizontal sight line at 25 km
plots,[cx,cx+scale*1000.],replicate(cy+scale*(re+25),2),/dev

; Mark off 100-km intervals along surface
FOR id=-15,15 do $
    radii,scale*(re-5),scale*(re+5),90-!radeg*((id*100.)/re),cx,cy,/dev

; Draw 40 km tangent ray from apogee
radii,0.,scale*re,-6.34,cx,cy+scale*(re+80.),/dev

; Draw horizontal segment from apogee
radii,0.,scale*400.,0.,cx,cy+scale*(re+80.),/dev

; Label depression angle
xyouts,cx+scale*300.,cy+scale*(re+80)-2.*!D.Y_CH_SIZE $
      ,'6.34!9%!x',/dev,charsize=2,charthick=4

; Label shells
xyouts,cx-!D.X_CH_SIZE,cy+scale*(re+80),'80 km',/dev,align=1
xyouts,cx-!D.X_CH_SIZE,cy+scale*(re+40),'40 km',/dev,align=1
xyouts,cx-!D.X_CH_SIZE,cy+scale*(re+10),'10 km',/dev,align=1

psclose

Return
END