Why do we define the freezing point of pure water as 0°C when most pure water does not freeze at that temperature? Instead, it can and does remain in the liquid phase down to temperatures as low as -48°C [Molinaro & Moore, 2011]. Cold-weather clouds throughout the Earth’s atmosphere consist primarily of water droplets at temperatures tens of degrees below 0°C. These droplets of liquid water are quite stable. They condense, collide, agglomerate, fragment, and vaporize—all without freezing. Most cumulonimbi (thunderheads) do not form their icy “anvil” until updraft ambient air temperatures approach -42°C. I am well aware that the abundance of exotic (non-water) icing nuclei on the Earth’s surface brings about surface freezing in the vicinity of 0°C, but such water is hardly “pure”. Water uncontaminated by such nuclei does not freeze at 0°C. Why then should the generally accepted scientific definition of water’s freezing point be 0°C?