There are three crucial factors that account for how land and water react differently to heating and cooling.
The first of these is that although both fluids and solids can be heated by solar radiation, fluids can absorb heat to some depth because they are transparent. Of course, this is dependent on the murkiness of the water, but in general, water is better at storing heat to some depth. Land, on the other hand absorbs all the net radiative gain within a few [G 14 / microns] of the surface.
The next is that the heat transfer in solids is accomplished by diffusion of heat from molecule to molecule. This is an extremely inefficient and slow process, which means that the lower layers of the land surface will only receive heat after a considerable time.
Finally heat transfer within fluids occurs through molecular diffusion as with solids, but additionally through mixing and turbulence, which is much more efficient. Turbulence occurs in the oceans because of the action of wind upon the surface of the water. Mixing can also occur through the sinking of heavier surface water which has cooled by radiative heat loss. These processes can mix heat absorbed in the surface layers to large depths, where it is stored. They can also bring warmer water to the surface, which had been stored at an earlier time, and replace water which had cooled.
