Answer
The air on land gets cooler and warmer faster than water because the air on land has a lower specific heat capacity than water.
Work Step by Step
Specific heat capacity is the amount of heat required to increase the temperature of one gram of a substance by 1$^{\circ}$celsius. The Specific heat capacity of water is more than the air, thus it requires more heat to increase the temperature of the water whereas less heat is required to increase the temperature of the land, making the land warmer and water cooler. Also, it takes more time to cool water than it takes to cool the air on the land.
