Latent Heat on Great Dodd

I came up with a new strategy to keep the milk fresh for brewing up after a long walk from Dunmail Raise north over Helvellyn and beyond: pack the milk with ice. The milk has come from the fridge and will eventually reach the ambient air temperature whatever happens. Thermal energy will flow from the warmer air into the milk until the milk and the air are at the same temperature. There is so much air that it will not noticeably decrease in temperature. The ice adds one complication: after the thermal energy raises the temperature of the ice to 0 degrees Celsius, the ice then needs to melt. Thermal energy flows in but the temperature doesn't rise. Because the thermal energy seems to disappear, it is called LATENT HEAT where latent means "hidden". The energy is actually being used to break the bonds that hold the molecules together as a solid. This uses up rather a lot of energy that would otherwise warm the milk up to ambient air temperature. Once the ice has melted, this process continues, warming ice and water up to air temperature eventually. Crucially, this takes longer so there is less chance of bacteria making my milk go off.