As we will see in a moment, water heats and cools more slowly than land. Therefore, San Francisco stays pretty warm in the winter, but warms up very little in the summer. A maritime climate, small annual temperature range. Wichita, isolate from any large body of water in the middle of North America, gets much hotter in summer and much colder in winter than does San Francisco. A continental climate, large annual temperature range.
Water molecules are slow to respond to heat gain or loss.
Over continents, a greater percentage of radiational surplus dissipation occurs by sensible heat flux. Water is transparent , light penetrates to about 200m depth. Solar energy received can be stored in a large volume. Land surface is opaque. Heat surplus concentrated immediately at soil surface.