How are large bodies of water able to moderate air temperature?

This is because of the high specific heat capacity of water. Water is a very unique substance in many ways. One of those ways is its ability to store high amounts of heat from its surroundings. Specific Heat Capacity is a measure of this. For instance, it takes 4.2J of energy to heat 1g of water by 1oC. It only takes about one tenth of that amount of energy to heat 1g of iron by 1oC This is why water is such a great coolant for car engines. It can store the heat energy from the engine, whilst not increasing its own temperature too much. Back to the large bodies of water. As the water comes into contact with hot air, the water can absorb heat energy, cooling down the air temperature.