Because of water's fluid molecular composition, it takes longer to heat and cool than land, which has a molecular structure that is more static and dense. Convective movements and the thermal capacities of bodies of water cause them to have a longer heat and cool time than land. Additionally the typically darker color of land gives it a higher propensity to trapping heat.Continue Reading
Because water is a liquid, its molecules are in greater motion than those of land, a solid. Like air, water is prone to convective movements and vertical mixing. Because water molecules are in constant motion, it takes longer for solar radiation to uniformly raise the temperature of a given body of water.
Large bodies of water like oceans have higher thermal capacities than land due to their immense density. As a result, it takes up to four times the amount of heat to raise the temperature of a given amount of water 1 C as it takes to raise the temperature of the same amount of land by an equivalent degree.
Color is also a factor. Because water is lighter than land, it reflects more solar radiation and does not heat as quickly.
Sunlight penetrates many meters into a body of water, whereas it only hits the upper, superficial portion of land. That is why it takes longer for water to cool than it does for land.Learn more about Earth Science