Specific Heat Capacity: Why Water Warms Slowly

Raising one kilogram of a substance by one degree Celsius takes a fixed amount of energy, its specific heat capacity, and the energy needed is E = mcΔθ. Water's value of about 4,200 J/kg°C is unusually high — roughly four times that of most metals — so the same heater warms a kilogram of copper far faster than a kilogram of water. That single number explains why coastal air swings less than inland air and why water is the working fluid in heating systems.