§3.1#11 Περὶ δὲ τῶν ὑπολοίπων εἴπωμεν ἔργων τῆς ἐκκρίσεως ταύτης, τὸν ὑφηγημένον ἢδη τρόπον λέγοντες.
1 Now let us speak of the remaining effects of this exhalation, following the method already indicated.
τὸ γὰρ πνεῦμα τοῦτο ἐκκρινόμενον κατὰ μικρὰ μὲν καὶ σποράδην διαχεόμενον καὶ πολλάκις γιγνόμενον καὶ διαπνέον καὶ λεπτομερέστερον ὂν βροντὰς ποιεῖ καὶ ἀστραπάς· ἂν δʼ ἀθρόον καὶ πυκνότερον, ἧττον δʼ ἐκκριθῇ λεπτόν, ἐκνεφίας ἄνεμος γίγνεται· διὸ καὶ βίαιος (τὸ γὰρ τάχος τῆς ἐκκρίσεως ποιεῖ τὴν ἰσχύν).
For this wind, when it is excreted in small quantities and dispersedly, being dispersed and occurring frequently, breathing through and being of finer parts, produces thunder and lightning; but if it is excreted all at once and denser, and less fine, it becomes the wind called eknephias; wherefore it is also violent (for the speed of its excretion produces its strength).
ὅταν μὲν οὖν συνακολουθήσῃ πολλὴ καὶ συνεχὴς ἔκκρισις, τὸν αὐτὸν γίγνεται τρόπον ὥσπερ ὅταν πάλιν εἰς τοὐναντίον ὁρμήσῃ· τότε γὰρ ὑετὸς καὶ ὕδατος γίγνεται πλῆθος.
Now, when a great and continuous excretion accompanies it, this occurs in the same way as when it rushes back in the opposite direction; for then rain and a quantity of water are produced.
ὑπάρχει μὲν οὖν ἄμφω δυνάμει ταῦτα κατὰ τὴν ὕλην· ὅταν δὲ ἀρχὴ γένηται τῆς δυνάμεως ὁποτερασοῦν, ἀκολουθεῖ συγκρινόμενον ἐκ τῆς ὕλης ὁποτέρου ἂν ᾖ πλῆθος ἐνυπάρχον πλέον, καὶ γίγνεται τὸ μὲν ὄμβρος, τὸ δὲ τῆς ἑτέρας ἀναθυμιάσεως ἐκνεφίας.
Now both of these exist potentially in the matter; but when the beginning of either potentiality occurs, that of which a greater quantity is pre-existing in the matter follows by being condensed, and the one becomes rain, while the other, from the second exhalation, becomes an eknephias.
ὅταν δὲ τὸ ἐκκρινόμενον πνεῦμα τὸ ἐν τῷ νέφει ἑτέρῳ ἀντιτυπήσῃ οὕτως ὥσπερ ὅταν ἐξ εὐρέος εἰς στενὸν βιάζηται ὁ ἄνεμος ἐν πύλαις ἢ ὁδοῖς (συμβαίνει γὰρ πολλάκις ἐν τοῖς τοιούτοις ἀπωσθέντος τοῦ πρώτου μορίου τοῦ ῥέοντος σώματος διὰ τὸ μὴ ὑπείκειν, ἢ διὰ στενότητα ἢ διὰ τὸ ἀντιπνεῖν, κύκλον καὶ δίνην γίγνεσθαι τοῦ πνεύματος· τὸ μὲν γὰρ εἰς τὸ πρόσθεν κωλύει προϊέναι, τὸ δʼ ὄπισθεν ἐπωθεῖ, ὥστε ἀναγκάζεται εἰς τὸ πλάγιον, ᾗ οὐ κωλύεται, φέρεσθαι, καὶ οὕτως ἀεὶ τὸ ἐχόμενον, ἕως ἂν ἓν γένηται, τοῦτο δʼ ἐστὶ κύκλος· οὗ γὰρ μία φορὰ σχήματος, τοῦτο καὶ αὐτὸ ἀνάγκη ἓν εἶναι)· ἐπί τε τῆς γῆς οὖν διὰ ταῦτα γίγνονται οἱ δῖνοι, καὶ ἐν τοῖς νέφεσιν ὁμοίως κατὰ τὴν ἀρχήν, πλὴν ὅτι, ὥσπερ, ὅταν ἐκνεφίας γίγνηται, ἀεὶ τὸ νέφος ἐκκρίνεται καὶ γίγνεται συνεχὴς ἄνεμος, οὕτως ἐνταῦθα ἀεὶ τὸ συνεχὲς ἀκολουθεῖ τοῦ νέφους· διὰ δὲ πυκνότητα οὐ δυνάμενον ἐκκριθῆναι τὸ πνεῦμα ἐκ τοῦ νέφους στρέφεται μὲν κύκλῳ τὸ πρῶτον διὰ τὴν εἰρημένην αἰτίαν, κάτω δὲ φέρεται διὰ τὸ ἀεὶ τὰ νέφη πυκνοῦσθαι, ᾗ ἐκπίπτει τὸ θερμόν.
But when the excreted wind in the cloud strikes against another, just as when the wind is forced from a wide place into a narrow one in gates or roads— (for it often happens in such cases that when the first part of the flowing body is pushed back because it does not yield, either due to narrowness or due to a headwind, a circle and whirlpool of the wind is formed; for while the obstacle prevents it from going forward, what is behind pushes it on, so that it is forced to move sideways where it is not prevented, and so always the next part, until it becomes one, and this is a circle; for that of which the motion of the figure is one must also itself be one)—on the earth, then, whirlwinds occur because of these causes, and in the clouds likewise in their beginning, except that, just as when an eknephias occurs, the cloud is always excreted and a continuous wind is produced, so here the continuous part of the cloud always follows; but the wind, being unable to be excreted from the cloud due to density, at first turns in a circle for the reason mentioned, and is carried downwards because the clouds are always condensing in the direction where the heat falls out.
καλεῖται δʼ, ἂν ἀχρωμάτιστον ᾖ, τοῦτο τὸ πάθος τυφῶν, ἄνεμος ὤν, οἷον ἐκνεφίας ἄπεπτος.
And this phenomenon, if it is colorless, is called a typhon, being a wind, as it were, an undigested eknephias.
βορείοις δʼ οὐ γίγνεται τυφῶν, οὐδὲ νιπτικῶς ἐχόντων ἐκνεφίας, διὰ τὸ πάντα ταῦτʼ εἶναι πνεῦμα, τὸ δὲ πνεῦμα ξηρὰν εἶναι καὶ θερμὴν ἀναθυμίασιν.
But a typhon does not occur when northerly winds blow, nor does an eknephias occur when it is snowy, because all these are wind, and wind is a dry and hot exhalation.
ὁ οὖν πάγος καὶ τὸ ψῦχος διὰ τὸ κρατεῖν σβέννυσιν εὐθὺς γιγνομένην ἔτι τὴν ἀρχήν.
Therefore, frost and cold, by dominating, immediately extinguish the beginning while it is still forming.
ὅτι δὲ κρατεῖ, δῆλον· οὐδὲ γὰρ ἂν ἦν νιφετός, οὐδὲ βόρεια τὰ ὑγρὰ· ταῦτα γὰρ συμβαίνει κρατούσης εἶναι τῆς ψυχρότητος.
And that they dominate is clear; for otherwise there would be no snowfall, nor would the moisture be northerly; for these things happen when coldness dominates.