Berachot 18b: The word reviah

Just a quick note of correction, because I've seen people making this mistake. Regarding this word on Brachot 18b:

הלכה היא ושטה ובאה ואמרה לה חברתה חברתי מה שמעת מאחורי הפרגוד אמרה לה שמעתי שכל הזורע ברביעה ראשונה ברד מלקה אותו הלך הוא וזרע ברביעה שניה של כל העולם כולו לקה שלו לא לקה

Or, in English:

So the other went and wandered about and returned. Said her companion to her: My dear, what have you heard from behind the curtain? She replied: I heard that whoever sows after the first rainfall¹³  will have his crop smitten by hail. So the man went and did not sow till after the second rainfall,¹⁴  with the result that everyone else's crop was smitten and his was not smitten.¹⁵ 

The word רביעה does not actually have anything to do with quarters. Rather, it means rainfall, and derives from fructification. To cite Jastrow: