When we turn our face towards the sun on a day with clear skies: Is the heat we feel on our skin actual heat radiation from the surface of the sun or do we just feel the warmth of the molecules in our atmosphere which have been “warmed” by radiation from the upper atmosphere?
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The warmth you feel from the sun is from the visible light hitting your skin, your skin absorbing some of that energy, then re-radiating it as longwave IR (heat). In fact, practically all the warmth on the planet is the result of visible light being converted into longwave IR. The sun doesn’t put out enough longwave IR to heat the planet at our distance.
What thermal radiation from the sun we receive is mostly absorbed by the upper atmosphere before it reaches the surface. Thanks to greenhouse gases, our atmosphere is relatively opaque to longwave IR so incoming radiation is pretty well taken care of long before it makes it to the lower part of the atmosphere.
For more information, look up black body radiation.
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