Panel (a): high-resolution (R = 0.02 cm⁻¹) log-scale comparison between observations (up) and the theory (down) for the methane absorption cross sections (cm²/molecule) in entire tetradecad range at two temperatures T = 600 K (green), and T = 1000 K (red). Panel (b): high-resolution (R = 0.02 cm⁻¹) comparison between observations (up) and the theory (down) for the methane absorption cross sections in the lower part of the tetradecad at two temperatures T = 600 K (green), and T = 1000 K (red). Panel (c): high-resolution (R = 0.02 cm⁻¹) comparison between observations (up) and the theory (down) for the methane absorption cross sections in the middle part of the tetradecad at two temperatures T = 600 K (green), and T = 1000 K (red). Panel (d): T-dependence of methane absorbance in the middle part of tetradecad at 8 temperatures, 295, 300, 400, 500, 600, 700, 800, 900, and 1000 K: comparison of observed (up) and theoretical (down) absorption cross sections under high resolution (R = 0.02 cm⁻¹).