Diathermancy

Diathermancy (from "dia" through and "thermē" heat) is the property of some fluids that allows rays of light through them without itself being heated. A diathermanous substance is thus "permeable" by heat. Diathermancy was first described by German physicist and chemist Heinrich Gustav Magnus in the 1800s.

Air is diathermanous; therefore atmospheric air is not heated by sunshine. Atmospheric air is heated by long-wave thermal radiation emitted by soil, and especially, by water on the Earth's surface.

Water is not diathermanous, and it is heated directly by sunshine.