Left panels: integrated intensities of [C ii], [N ii], and ¹³CO (dashed line) over the velocity range 100 to 125 km s^-1 versus latitude. The symbols indicate how many SOFIA LOS were averaged to calculate the emission intensity. The ¹³CO intensity profile is computed using the GRS data cube and we show only high latitude values to demonstrate how sharply it drops to nearly zero by b = 0.̊5. ¹³CO has a much smaller scale height than [C ii] and [N ii]. Right panels: integrated intensities of [C ii] and [N ii] over the velocity range 110 to 125 km s^-1 versus latitude. There is no measurable ¹³CO in this velocity range, and the [C ii] and [N ii] arise solely from the WIM. The exponential curves correspond to exp(− (b−δb) /b₀) with δb = −0.̊05 and b₀ = 0.̊45.