Upper panel: correlation of the temperature asymmetry with respect to the 21 cm velocity field within ten ellipses with major axes between 0.1° and 0.8° (black line) and for the ellipse with position angle rotated by 34° (red line). Central panel: radial profile, in μK for the temperature asymmetry in the 70 GHz Planck band (black curve) and for the 21 cm DRAO data relative to the M 33 HI velocity field (red profile, in km s^-1) in Fig. 3. Bottom panel: temperature and velocity radial profiles, but with the temperature and velocity asymmetry calculated shell by shell.