How does the heating and cooling rates of land and water compare?

Answer 1

In general the land surface, being darker and less reflective, will absorb a great deal of solar radiation, and will have a significant increase in temperature on a bright sunny day. The ocean, at the same time, will reflect a greater portion of the radiation, and in addition, since water has such a high thermal coefficient, will have a much smaller increase in temperature. Thirdly, the water will spread the radiation to a depth that is not possible on the land. For all these reasons the water will remain cooler than the land on sunny day.

At night, the darker colours of the land will cause it to radiate its heat quickly, and its temperature will drop rapidly. The water will radiate more slowly, has a greater heat 'reserve' due to its high thermal coefficient, and as the surface cools, it will be displaced by warmer water from below due to the density changes that occur. As a result, an hour or so after sunset, the ocean will be warmer than the land, and will remain so for a large part of the night.