How come Mars cools off so rapidly at night? You'd think, given the enormous amount of greenhouse gasses (principally CO2) in Mars' atmosphere, that locations on Mars would cool off much more slowly at night than they do on Earth since Mars has much, much more CO2 in it's atmosphere than Earth does, over 20x more on a per unit surface area basis, yet Mars has a massive whoppingly large gap between daytime high temperatures and nighttime lows. Theres nowhere on Earth, not even the most arid regions, that regularly experiences daily 70ºC temperature swings, but on Mars thats the norm.
Is it possible that the greenhouse gas qualities of CO2 are negligible or insignificant? Water vapor is the principle greenhouse gas on Earth, if CO2 was completely impotent as a greenhouse gas then that would explain why Mars has such massive daily temperature swings in comparison to the much more moderate ones on Earth. Some humid regions on Earth have daily average temperature variations as small as 5ºC while arid locations swing by as much as 15ºC on average. There is nothing anywhere approaching the temperature variations seen on Mars.
Attached is a location on Mars near the equator with it's monthly temperature statistics normalized to an Earth calendar for ease of comparison