A more mundane explanation is that hot water evaporates faster than cold, decreasing its volume and thus the time it takes to freeze.
[Edit - Cannot delete my comment now. As 'ketzo' points out below my point is not same as OP's. OP points out that hot water is less dense. Maybe less dense liquid cools faster]
That quoted sentence says that hot water loses volume compared to cold water.
The person you’re replying to is saying that hot water simply takes up more space as well.
- 1 m³ of hot water is less water (in terms of mass) than 1 m³ of cold water
- 1 kg of hot water has a bigger surface area than 1 kg of cold water
I am still not convinced that this alone would explain such a phenomena. I'd rather believe there is some weird fluid dynamics and layering involved.
The singular is "phenomenon".
The second less so. Hot water has a bigger surface area, which makes heat loss fast at first. When it gets to cold water's temp it should have the same surface area as the cold water making the advantage disappear.
> Water is a strange substance, less dense when solid than liquid, and with solid and liquid phases that can coexist at the same temperature.
> the Mpemba effect could happen through a related mechanism that Raz has previously described with Lu in systems that undergo a second-order phase transition, meaning that their solid and liquid forms can’t coexist at the same temperature. Water is not such a system (it has first-order phase transitions),
This is where BTUs come in handy..