Since it is a sensation experience and common language rather than technical
Everyday communication is more often than not non-technical in order for all participants to take part without requiring a technical understanding provided by training, experiences, etc. The redundancy in language, in part but not all, is due to this gap between expert and layman.
Wrong.
The technical (or more properly, Greek and Latin) terms do not contain the necessary associations that we culturally have with the "common" (again more properly, English) ones.
That is to say, "thermal radiation" doesn't conjure feelings of winter covers, hugs from kith and kin, and other things we might describe as "intimate."
This is how Modern English distinguishes contexts and classes. Common, intimate things are described with words that generally come from Old English. Sophisticated, "high-class" things are described with French loanwords. (Consider this example: what different images are conjured by these two phrases which technically mean the same thing: "a hearty welcome"/"a cordial reception.") Meanwhile, scientific matters are described with Greek and Latin terms, probably because those languages are associated in our culture with the "people from the great past who are superior in intellect and achievement to us dirty English-speaking
peasants."
Your experience is relevant since you are identifying the sun as the source of said "warmth" to you rather than another source say a geothermal vent. This source of warmth must include the mechanic that generate what you feel. Otherwise you can not identify the source of said warmth with justification.
Why is "justification" needed for an experience, something which is inherently subjective? Sun provides warmth regardless of whether she's a ball of plasma or a giant firebird, and she's always provided the same warmth regardless of what peoples in the past thought she was. You may notice that I'm using the "she" pronoun to refer to her, which is mostly from tradition: Sun is no more "female" than "male", which is how the Romance languages gender her. Yet it's not just tradition; "it" simply does not sufficiently convey my experience of Sun, despite technically being "correct" in Modern English.
Do you understand what I mean when I say "experience"?