How does volume come into play? Well because the higher the surface area to volume ratio of a spheroid body is, the more efficiently it interacts with its surroundings, in this case by radiation.
That said, you haven't said a thing to support the position that Venus's atmosphere is the causal factor, and not a consequence of solar inputs. There's no reason to believe we can learn anything about the Earth's atmosphere from Venus than there is we can from Mercury.
Look this isn't that hard. Venus has the atmosphere it does because it used to absorb far more sunlight than it does now which caused the increased albedo.
How does volume come into play? Well because the higher the surface area to volume ratio of a spheroid body is, the more efficiently it interacts with its surroundings, in this case by radiation.
That said, you haven't said a thing to support the position that Venus's atmosphere is the causal factor, and not a consequence of solar inputs. There's no reason to believe we can learn anything about the Earth's atmosphere from Venus than there is we can from Mercury.
Look this isn't that hard. Venus has the atmosphere it does because it used to absorb far more sunlight than it does now which caused the increased albedo.