My question is essentially: how can I read from this graph the actual total energy absorbed by the earth?
Is it true that the total red area is equal to the solar radiation energy absorbed by the earth's surface?
Or is the total red area merely the solar radiation that arrives at the earth's surface. What does the graph denoting the actual absorption look like? If the surface reflects the different wavelengths at different rates, then the shape should be different.
I.e. practically, if I am in my room, and the sun is emitting energy through my window which heats my room, is most of that heat energy coming from infrared and visible (and not from UV)?