Projected prolate spheroid (orange) overlaid on the dust optical depth map at 353 GHz, τ ₃₅₃, from Planck Collaboration XI (2014), with 1 K and 2 K contours of the brightness temperature map of the NCPL region from EBHIS data at v = 16.85 km s⁻¹ overlaid in solid cyan. Red arcs show the location of the moving warm H I gas.