In hot climates, water is often stored in porous clay pots. A small amount of water seeps through the clay to the outer surface. This helps to keep the water inside the pot cool.
Why does this process reduce the temperature of the water?
The most energetic water molecules evaporate from the outer surface, leaving the remaining water cooler.
Clay has an extremely high specific heat capacity, which prevents heat from entering.
The water on the outer surface acts as an insulating layer against any incoming thermal radiation.
Liquid water is always at a lower temperature than the surrounding air.
528 exam-style questions on CIE IGCSE Physics 2.2 Thermal properties and temperature, covering 2.2.1 Thermal expansion of solids, liquids and gases, 2.2.2a Internal energy and temperature, 2.2.2b Specific heat capacity, 2.2.3a Melting, boiling, condensation and solidification, 2.2.3b Evaporation, and 2.2.3c Cooling by evaporation. Each one has a worked solution and a mark scheme showing where the marks go.