On Mars, a world nearly stripped of atmosphere, the ground near the equator can reach temperatures above freezing at noon while the air at head height remains deeply frozen — a vertical temperature swing of 26 degrees Celsius per meter that no human body has yet had to reckon with directly. NASA's Perseverance rover has measured this phenomenon with precision in Jezero Crater, revealing that the same scarcity of air that makes Mars so silent also makes it thermally incoherent in ways Earth never is. Where our own planet's dense, restless atmosphere quietly smooths temperature into something we