Now many cities have built artificial lakes, which not only beautify the environment, but also regulate the climate. It uses the nature of water to regulate the climate. If it's artificial,

Because of the large specific heat capacity of water, during the day, water with the same quality absorbs the same heat than sand, and the temperature of water rises less; The same heat is released at night, and the temperature of water is reduced less, which makes the temperature difference between day and night small and can effectively adjust the climate;

Heat absorbed by water: q absorption =cm△t=4.2x 103J/(kg? ℃)× 1× 107kg×3℃= 1.26× 10 1 1J。

So the answer is: large specific heat capacity; 1.26× 10 1 1.