55km is not insignificant though. Some very rough estimates - 55km is 0.5% of the distance from the equator to the pole. If the temperature range between those

55km is not insignificant though. Some very rough estimates - 55km is 0.5% of the distance from the equator to the pole. If the temperature range between those two extremes is 50C then the shift corresponds to a net cooling of 0.25C, which seems like it would have a noticable impact on those graphs. Obviously there is more to it than that, but I don't think it makes it a non-issue.