§1.1010 ἐκ δὲ τοῦ καθʼ ἡμέραν ἀτμίζοντος ὅσον ἂν μὴ μετεωρισθῇ διʼ ὀλιγότητα τοῦ ἀνάγοντος αὐτὸ πυρὸς πρὸς τὸ ἀναγόμενον ὕδωρ, πάλιν καταφερόμενον ὅταν ψυχθῇ νύκτωρ, καλεῖται δρόσος καὶ πάχνη, πάχνη μὲν ὅταν ἡ ἀτμὶς παγῇ πρὶν εἰς ὕδωρ συγκριθῆναι πάλιν (γίγνεται δὲ χειμῶνος, καὶ μᾶλλον ἐν τοῖς χειμερινοῖς τόποις), δρόσος δʼ ὅταν συγκριθῇ εἰς ὕδωρ ἡ ἀτμίς, καὶ μήθʼ οὕτως ἔχ ἡ ἀλέα ὥστε ξηρᾶναι τὸ ἀναχθέν, μήθʼ οὕτω ψῦχος ὥστε παγῆναι τὴν ἀτμίδα αὐτὴν διὰ τὸ ἢ τὸν τόπον ἀλεεινότερον ἢ τὴν ὥραν εἶναι·
10 But of the moisture evaporating during the day, whatever is not raised high because of the smallness of the fire raising it in relation to the water being raised, when it is carried down again as it cools at night, is called dew and hoar-frost. Hoar-frost indeed occurs when the vapor freezes before condensing again into water (and it occurs in winter, and more in wintry places), but dew when the vapor condenses into water, and the warmth is neither so great as to dry up what was raised, nor the cold so great as to freeze the vapor itself, because either the region or the season is warmer.
γίγνεται γὰρ μᾶλλον ἡ δρόσος ἐν εὐδίᾳ καὶ ἐν τοῖς εὐδιεινοτέροις τόποις, ἡ δὲ πάχνη, καθάπερ εἴρηται, τοὐναντίον·
For dew occurs rather in calm weather and in calmer places, but hoar-frost, as has been said, the contrary.
δῆλον γὰρ ὡς ἡ ἀτμὶς θερμότερον ὕδατος (ἔχει γὰρ τὸ ἀνάγον ἔτι πῦρ), ὥστε πλείονος ψυχρότητος αὐτὴν πῆξαι.
For it is clear that vapor is warmer than water (for it still contains the fire that raised it), so that it requires more cold to freeze it.
γίγνεται δʼ ἄμφω αἰθρίας τε καὶ νηνεμίας· οὔτε γὰρ ἀναχθήσεται μὴ οὔσης αἰθρίας, οὔτε συστῆναι δύναιτʼ ἂν ἀνέμου πνέοντος.
Both occur in clear and windless weather; for it will neither be raised if the sky is not clear, nor could it condense if a wind is blowing.
σημεῖον δʼ ὅτι γίγνεται ταῦτα διὰ τὸ μὴ πόρρω μετεωρίζεσθαι τὴν ἀτμίδα· ἐν γὰρ τοῖς ὄρεσιν οὐ γίγνεται πάχνη.
And it is a sign that these things occur because the vapor is not raised far: for on mountains hoar-frost does not occur.
αἰτία δὲ μία μὲν αὕτη, ὅτι ἀνάγεται ἐκ τῶν κοίλων καὶ ἐφύδρων τόπων, ὥστε καθάπερ φορτίον φέρουσα πλέον ἡ ἀνάγουσα θερμότης ἢ καθʼ ἑαυτὴν οὐ δύναται μετεωρίζειν ἐπὶ πολὺν τόπον αὐτὸ τοῦ ὕψους, ἀλλʼ ἐγγὺς ἀφησι πάλιν· ἑτέρα δʼ ὅτι καὶ ῥεῖ μάλιστα ὁ ἀὴρ ῥέων ἐν τοῖς ὑψηλοῖς, ὃς διαλύει τὴν σύστασιν τὴν τοιαύτην.
And one cause is this, that it is raised from hollow and watery places, so that the raising warmth, carrying as it were a heavier load than it can bear by itself, cannot raise it to a great height, but soon lets it go again; another is that the air flowing in high places flows most, which dissolves such condensation.
γίγνεται δʼ ἡ δρόσος πανταχοῦ νοτίοις, οὐ βορείοις, πλὴν ἐν τῷ Πόντῳ.
Dew occurs everywhere with south winds, not north winds, except in Pontus.
ἐκεῖ δὲ τοὐναντίον· βορείοις μὲν γὰρ γίγνεται, νοτίοις δʼ οὐ γίγνεται.
There the contrary happens: for it occurs with north winds, but not with south winds.
αἴτιον δʼ ὁμοίως ὥσπερ ὅτι εὐδίας μὲν γίγνεται, χειμῶνος δʼ οὔ· ὁ μὲν γὰρ νότος εὐδίαν ποιεῖ, ὁ δὲ βορέας χειμῶνα· ψυχρὸς γάρ, ὥστʼ ἐκ τοῦ χειμῶνος τῆς ἀναθυμιάσεως σβέννυσι τὴν θερμότητα.
And the cause is similar to why it occurs in calm weather but not in winter; for the south wind produces calm, but the north wind winter; for it is cold, so that because of the winter it extinguishes the warmth of the exhalation.
ἐν δὲ τῷ Πόντῳ ὁ μὲν νότος οὐχ οὕτως ποιεῖ εὐδίαν ὥστε γίγνεσθαι ἀτμίδα, ὁ δὲ βορέας διὰ τὴν ψυχρότητα ἀντιπεριιστὰς τὸ θερμὸν ἀθροίζει, ὥστε πλέον ἀτμίζει μᾶλλον.
But in Pontus, the south wind does not produce calm so as to cause vapor, while the north wind, on account of its coldness, by counter-acting concentrates the warmth, so that it rather evaporates more.
πολλάκις δὲ τοῦτο καὶ ἐν τοῖς ἔξω τόποις ἰδεῖν γιγνόμενον ἔστιν· ἀτμίζει γὰρ τὰ φρέατα βορείοις μᾶλλον ἢ νοτίοις· ἀλλὰ τὰ μὲν βόρεια σβέννυσιν πρὶν συστῆναί τι πλῆθος, ἐν δὲ τοῖς νοτίοις ἐᾶται ἀθροίζεσθαι ἡ ἀναθυμίασις.
And one can often see this happening also in external places; for wells evaporate more with north than with south winds; but the north winds extinguish it before any quantity can condense, while with south winds the exhalation is allowed to accumulate.
αὐτὸ δὲ τὸ ὕδωρ οὐ πήγνυται, καθάπερ ἐν τῷ περὶ τὰ νέφη τόπῳ.
But the water itself does not freeze, as it does in the region around the clouds.
§1.1111 ἐκεῖθεν γὰρ τρία φοιτᾷ σώματα συνιστάμενα διὰ τὴν ψύξιν, ὕδωρ καὶ χιὼν καὶ χάλαζα.
11 For from there three bodies come, being condensed through cooling: water, snow, and hail.
τούτων δὲ τὰ μὲν δύο ἀνάλογον καὶ διὰ τὰς αὐτὰς αἰτίας γίγνεται τοῖς κάτω, διαφέροντα τῷ μᾶλλον καὶ ἧττον καὶ πλήθει καὶ ὀλιγότητι· χιὼν γὰρ καὶ πάχνη ταὐτόν, καὶ ὑετὸς καὶ δρόσος, ἀλλὰ τὸ μὲν πολὺ τὸ δʼ ὀλίγον.
Of these, two are analogous and occur due to the same causes as those below, differing in degree and in quantity; for snow and hoar-frost are the same, and rain and dew, but the former is much and the latter is little.
ὁ μὲν γὰρ ὑετὸς ἐκ πολλῆς ἀτμίδος γίγνεται ψυ χομένης· τούτου δʼ αἴτιον ὅ τε τόπος πολὺς καὶ ὁ χρόνος ὥν, ἐν ὁ συλλέγεται καὶ ἐξ οὗ.
For rain occurs from much vapor being cooled; and the cause of this is that both the region is large and the time is long, in which and from which it is collected.
τὸ δʼ ὀλίγον ἡ δρόσος· ἐφήμερος γὰρ ἡ σύστασις καὶ ὁ τόπος μικρός· δηλοῖ τε ἥ τε γένεσις οὖσα ταχεῖα καὶ βραχὺ τὸ πλῆθος.
But dew is the little; for its condensation is only for a day, and the region is small; and this is shown both by its generation being rapid and its quantity small.
ὁμοίως δὲ καὶ πάχνη καὶ χιών· ὅταν γὰρ παγῇ τὸ νέφος, χιών ἐστιν, ὅταν δʼ ἡ ἀτμίς, πάχνη.
Likewise also hoar-frost and snow; for when the cloud freezes, it is snow, but when the vapor, hoar-frost.
διὸ ἢ ὥρας ἢ χώρας ἐστὶν σημεῖον ψυχρᾶς· οὐ γὰρ ἂν ἐπήγνυτο ἔτι πολλῆς ἐνούσης θερμότητος, εἰ μὴ ἐπεκράτει τὸ ψῦχος· ἐν γὰρ τῷ νέφει ἔτι ἔνεστιν πολὺ θερμὸν τὸ ὑπόλοιπον τοῦ ἐξατμίσαντος ἐκ τῆς γῆς τὸ ὑγρὸν πυρός.
Therefore it is a sign of either a cold season or a cold country; for it would not freeze, since there is still much warmth in it, unless the cold prevailed; for in the cloud there is still much warmth, the remnant of the fire that evaporated the moisture from the earth.
χάλαζα δʼ ἐκεῖ μὲν γίγνεται, ἐν δὲ τῷ πλησίον τῆς γῆς ἀτμίζοντι τοῦτʼ ἐκλείπει· καθάπερ γὰρ εἴπομεν, ὡς μὲν ἐκεῖ χιών, ἐνταῦθα γίγνεται πάχνη, ὡς δʼ ἐκεῖ ὑετός, ἐνταῦθα δρόσος· ὡς δʼ ἐκεῖ χάλαζα, ἐνταῦθα οὐκ ἀνταποδίδωσι τὸ ὅμοιον.
But hail occurs there, whereas in the vapor near the earth this is absent; for just as we said, as there is snow there, here hoar-frost occurs, and as there is rain there, here dew occurs; but as there is hail there, here there is no corresponding equivalent.
τὸ δʼ αἴτιον εἰποῦσι περὶ χαλάζης ἔσται δῆλον.
And the cause will be clear to those who speak about hail.