You visit a beach on a warm summer day. As you walk across the sand, you notice that it’s very hot, but just a few inches below the surface, it’s much cooler. Later, you walk into the water. Standing about knee-deep, you notice that the water temperature doesn’t change from the surface to the bottom.
a. Explain why there is a great temperature difference between the beach surface and a few inches down.
b. Explain why there is little difference in the water temperature between the surface and a foot down.(Hint: consider the materials involved. “Mixing” is not the right answer.)





