visarga-kāla (visargakāla); Charaka pairs it with dakṣiṇāyana; opposite: ādāna-kāla / uttarāyaṇa: what the term means and how it is translated

Charaka SamhitaSutrasthana 6 (Tasyashitiya Adhyaya):Standard (Trikamji) 6/4, Devanagari read on carakasamhitaonline.com: 'इह खलु संवत्सरं षडङ्गमृतुविभागेन विद्यात्| तत्रादित्यस्योदगयनमादानं च त्रीनृतूञ्छिशिरादीन् ग्रीष्मान्तान् व्यवस्येत्, वर्षादीन् पुनर्हेमन्तान्तान् दक्षिणायनं विसर्गं च||४||'. Kaviratna prints his number 2 after this passage (he numbers the opening verse 1). Both systems recorded; not converted. · checked against the source

For the purposes of this lesson, the year should be known as consisting of six portions, divided according to the seasons. Of these, the three seasons commencing with the season of dews and ending with summer constitute the period when the Sun travels in the region lying to the north of the equinoctial. That is again the period when the Sun takes (i. e., sucks up the liquid portion of every earthly object). The three other seasons commencing with the season of rains and ending with Hemanta constitutes the period of the Sun's southerly course. That is, besides, the time when the Sun gives (or yields moisture to all earthly objects).*2

Charaka's definition: the year has six seasons; the sun's northern course (udagayana) is ādāna and comprises śiśira, vasanta, grīṣma; the southern course (dakṣiṇāyana) is visarga and comprises varṣā, śarad, hemanta. Kaviratna's parenthetical glosses ('sucks up the liquid portion', 'yields moisture') are his, not the text; his footnote on the Indian calendar months is a translator's note.

Charaka SamhitaSutrasthana 6:Standard (Trikamji) 6/5, Devanagari read on carakasamhitaonline.com: 'विसर्गे पुनर्वायवो नातिरूक्षाः प्रवान्ति, इतरे पुनरादाने; सोमश्चाव्याहतबलः शिशिराभिर्भाभिरापूरयञ्जगदाप्याययति शश्वत्, अतो विसर्गः सौम्यः| आदानं पुनराग्नेयं; तावेतावर्कवायू सोमश्च कालस्वभावमार्गपरिगृहीताः कालर्तुरसदोषदेहबलनिर्वृत्तिप्रत्ययभूताः समुपदिश्यन्ते||५||'. Kaviratna splits this one Trikamji unit into his aphorisms 3 ('...Hence the period of Giving is mild (and agreeable).') and 4 ('The period of Taking is fiery...'). No one-to-one mapping; both recorded. · checked against the source

During the period when the Sun gives, the winds are not very dry; they also blow (without being deprived of motion). The winds of the period when the Sun takes have opposite virtues. The Moon, during the former period, appears with unabated vigor and, filling the universe with cool rays gladdens it every day. Hence the period of Giving is mild (and agreeable).3 The period of Taking is fiery. These two periods, the Sun and the winds, and the Moon also, as the learned instruct us, are subject to the influences of Time, of their own respective natures, and of track, and become the determining causes of time, season, moisture, faults, and strength of body.4

Visarga is saumya (Kaviratna: 'mild (and agreeable)'), ādāna is āgneya ('fiery'); the moon is unimpaired in visarga. 'Moisture' = rasa and 'faults' = doṣa are Kaviratna's words.

Charaka SamhitaSutrasthana 6:Standard (Trikamji) 6/7 (prose on strength increasing in varṣā-śarad-hemanta) and 6/8 (verse on strength at the start/middle/end of visarga and ādāna), Devanagari read on carakasamhitaonline.com: '||७|| वर्षाशरद्धेमन्तेषु तु दक्षिणाभिमुखेऽर्के ... तत्र बलमुपचीयते नृणामिति', '||८|| भवन्ति चात्र- आदावन्ते च दौर्बल्यं विसर्गादानयोर्नृणाम्| मध्ये मध्यबलं, त्वन्ते श्रेष्ठमग्रे च निर्दिशेत्'. Kaviratna prints 6 after the prose and restarts his count at 1 for the verse. Both recorded; not converted. · checked against the source

In the season, however, of rains, of Çarat, and of Hemanta, when the Sun begins his southerly course, and his powers become weakened by time, by the virtue of his track itself, by the winds generated by the clouds, and by the downpours (from the cloudy regions), when the Moon also appears with unabated vigor, and (lastly) when the heat of the universe becomes cooled by the water that falls from the clouds, moisture that is cool, sour, saltish, and sweet, increases gradually, and the strength of human beings increases.6 On this topic are the following verses :— It should be said that during the first season of the Giving period, (viz., the season of rains), and the last season of the Taking period, (viz., summer), men become weak. In the two intermediate seasons of both the periods, (viz., Çarat and Vasanta), men become neither very weak nor very strong. During the last season of the Giving period, (viz., Hemanta), and the first of the Taking period, (viz., Çiçira), the strength of men is at its highest.1

The physiological point of the term: in visarga, unctuous (arūkṣa) sour, salty and sweet rasas increase and human strength accumulates; strength is lowest at the start of visarga (varṣā) and end of ādāna (grīṣma), highest at the end of visarga (hemanta) and start of ādāna (śiśira). The season names in parentheses in the verse are Kaviratna's insertions. OCR renders ś as 'Ç' ('Çarat', 'Çiçira').

Sushruta SamhitaSutrasthana 6 (Ṛtucaryā Adhyāya):Bhishagratna prints no verse numbers (chapter-level). The Sanskrit sūtra is Sushruta Sutrasthana 6.7, confirmed in a printed edition: Suśrutasaṃhitā with Dalhaṇa's Nibandhasaṃgraha, ed. Jādavji Trikamji Āchārya, Nirnaya Sagar Press, Bombay 1915, Sūtrasthāna adhyāya 6, p. 23, where the mūla ends 'uttarottaraṃ ca sarvaprāṇināṃ balamupahīyate ७' and Dalhaṇa's gloss on it closes ॥७॥; the edition's table of contents lists '7 dakṣiṇottarabhedenāyanavibhāgaḥ, p. 23'. (तयोर्दक्षिणं वर्षाशरद्धेमन्ताः ... उत्तरं च शिशिरवसन्तग्रीष्माः ...) · checked against the source

The rains, autumn and Hemanta follow one another in succession when the sun is over the Tropic of Capricorn or is in the Winter Solstice (Dakshinayana) and the moon gains in strength in this part of the year. Rasas (Serum or sap) possessed of acid, saline and sweet tastes, grow strong and become dominant when the sun is over the Tropic of Capricorn (Dakshinayana) and all beings gain in strength and energy more and more. Winter, spring and summer mark the passing of the sun over the Summer Solstice (Uttarayana). The sun grows stronger in heat and light, and saps (rasas) of bitter, pungent and sour tastes increase in intensity, and all animals gradually begin to lose strength and energy.

Sushruta's parallel: the dakṣiṇa ayana (rains, autumn, hemanta) strengthens the moon (soma), makes the sour-salty-sweet rasas strong and progressively increases the strength of all beings; the uttara ayana (śiśira, spring, summer) strengthens the sun and progressively diminishes strength. Bhishagratna's 'Summer Solstice (Uttarayana)' and 'Tropic of Capricorn / Winter Solstice (Dakshinayana)' are his astronomical glosses, not in the Sanskrit, and doctrinally odd (uttarāyaṇa begins at the winter solstice); do not record them as what the text says. His 'bitter, pungent and sour' for the ādāna rasas is a slip: the printed Trikamji edition reads tikta-kaṣāya-kaṭuka (bitter, astringent, pungent) and Dalhaṇa re-quotes the same, agreeing with Charaka Su 6/6. Dalhaṇa also notes that most copies read the sūtra with the uttarāyaṇa first ('te śiśiravasantagrīṣmavarṣāśaraddhemantāḥ'), and defends his text's dakṣiṇāyana-first order on the ground that visarga is what gives beings strength; so the order in which the two halves are printed is itself a known variant.

Ashtanga HridayaSutrasthana 3 (Ritucharya Adhyaya):Verses 1-4 as numbered on ahsutrasthana.blogspot.com (verse 3 incipit: 'ऋतवो दक्षिणायनम् । वर्षादयो विसर्गश्च यद्बलं विसृजत्ययम् । सौम्यत्वादत्र सोमो हि बलवान् हीयते रविः'); not checked against a printed Sanskrit edition. · address only, nothing quoted to check

Vagbhata supplies the etymology behind the modern rendering 'release': visarga is so called because it releases (visṛjati) strength to beings. The 'Ashtanga Hridaya' etymology should not be attributed to Charaka, whose 6/4-5 gives no etymology.