Figure 6:
Mixing ratios of acetylene (left) and ethane (right) on Neptune as a function of season (represented by solar longitude Ls) at 1.1 × 10−3 mbar (top), 0.01 mbar (second from top), 0.1 mbar (third from top), and 1 mbar (bottom). Results are shown for five different latitudes: −9° (red), −27° (orange), −45° (green), −63° (blue), and −81° (magenta). Seasonal variations are are prominent at lower pressures (higher altitudes) but become muted at higher pressures (lower altitudes), and are much greater at high latitudes than low latitudes. The 81° S latitude region receives no direct sunlight for an extended period during the winter, leading to a strong minimum during that period. Note also that the position of the minimum mixing ratio shifts to later in the year as the pressure increases in the atmosphere. (For interpretation of the references to color in this figure legend, the reader is referred to the online version of this article.)