Not sure how to clearly ask this question. It’s puzzled me for a long time.
In the northern hemisphere the Sun begins it upward northern motion on the winter solstice (Capricorn/starved) and becomes exalted/proud at the spring equinox. How is the Sun still considered to be in the same weakness and strength at these points in both hemispheres when the quantity of light is opposite?
The Sun begins it northern motion at the same time in both hemispheres. At the ascending equinox ("vernal equinox" in the northern hemisphere) the Sun is just ascending over the equator. At the Cancer solstice the Sun is at its most northern position from the equator. That is true in both hemispheres, and that is what the tropical zodiac is based on.
As to the quantity of light being opposite, it is an interesting question. The direct answer in regard to tropical astrology is that the quantity or quality of light is not relevant, because the quantity and quality of light don't have anything to do with where Aries, Capricorn, etc. are. That doesn't mean the light doesn't have any impact whatsoever, just that the signs are not a place where you would see that impact.
This is great feedback and has helped my processing.
Tropical system is a seasonal system according to spring equinox being 0 Aries for the Northern Hemisphere. The point you bring up @vaknath is pertinent. Aries is Mesha, both names denoting the goat or a ram which has the connotations of spring and breaking though of growth from winter. Libra or Tula is a measurement of weight, which is an indication of the harvest of autumn from the summer growth. The experience for these is opposite in the southern hemisphere so perhaps the question remains about evaluating the Sun for the Southern Hemisphere.
It’s interesting to contemplate the Sun being exalted in the southern hemisphere as the days are becoming shorter. I see the sun moving through changing/fixed/mutable signs simultaneously in both hemispheres. The question is, how does the sun’s avasthas stay the same regardless of the hemisphere?
These responses have been very helpful.