1. "Mashiv Haruach Umorid Hageshem"
2. "Morid Hatal" in the Rainy Season
3. "Barech Alenu" - "Ten Tal Umatar Livracha"
4. Mistake in the Winter
5. Repeating Ninety Times
"Mashiv Haruach Umorid Hageshem"
The Rambam writes (Hilchot Tefilah 2:15): "Throughout the rainy season we include 'Mashiv Haruach Umorid Hageshem' in the second benediction of the Shmoneh Esreh prayer, and 'Morid Hatal' in the sunny season. When do we begin saying 'Mashiv Haruach Umorid Hageshem'? From the Mussaf prayer on the last holiday of Sukkot [Shemini Atzeret] until the Shacharit (morning) prayer on the first day of Passover. From the Mussaf prayer on the first day of Passover we say 'Morid Hatal.' "
It used to be that Jews living in the Diaspora would not say "Morid Hatal" in the summer; they would say only "Ten Beracha." The practical implication is that if one said neither "Mashiv Haruach Umorid Hageshem" nor "Morid Hatal" in the winter, he would have to repeat his prayer (see Berachot 29a; Shulchan Aruch 114:5). Today, Ashkenazi Jews living in Israel say "Morid Hatal.""Morid Hatal" in the Rainy Season
If one mistakenly says "Morid Hatal" instead of "Mashiv Haruach Umorid Hageshem" in the rainy season, the law is as follows: If he realizes his mistake before finishing [i.e., pronouncing God's name in] the "Mechayeh Hametim" blessing, he must return to "Atah Gibor" and insert "Mashiv Haruach Umorid Hageshem." However, if he already said God's name in the "Mechayeh HaMetim" blessing, he need not return, for "Mashiv Haruach Umorid Hageshem" is only a form of praise, not a prayer or request for rain (see Shulchan Aruch, Orach Chaim 114:5, 6)."Barech Alenu" - "Ten Tal Umatar Livracha"
A person should always familiarize himself with an uncommon prayer (one that has not been recited in the past thirty days) before reciting it. Therefore, before Maariv (the evening prayer) on 7 Marcheshvan, one should familiarize himself with the "Barech Alenu" prayer, or read it through (without reciting God's name), and when actually praying one should read it from the prayer book (Shulchan Aruch 100). According to the Rema, one who prays from a prayer book need not familiarize himself with the prayer.
From 7 Marcheshvan we begin requesting rain in the ninth benediction of the Shemoneh Esreh prayer, inserting the words, "Veten Tal Umatar Livracha Al Pene Ha'adama" ("And give dew and rain for a blessing upon the face of the earth"). The sages chose this date in order to give Sukkot pilgrims time to return home from Jerusalem before the rains (Shulchan Aruch 117:1).
And the Rambam writes (Hilchot Tefillah 2:16): "From 7 Marcheshvan we request rain in 'Birkat Shanim' [and we continue doing so] as long as we mention rain [in the 'Mechaye Hametim' blessing]. This relates to the land of Israel, but in Shinar (Mesopotamia) and in Syria and in Egypt and in regions adjacent and similar to these, we request rain from sixty days after the Tishrei cycle." Mistake in the Winter
If in the rainy season, after 7 Marcheshvan, one said "Barchenu" (according to Sephardi custom) or "Ten Beracha" (according to Ashkenazi custom) instead of requesting rain, his request in incomplete, and he must therefore repeat his prayer, this time asking for rain. However, if one noticed his mistake before completing his prayer, he may request rain in other places in the Shemoneh Esreh prayer as well:
1. If a person realized his mistake after completing "Birkat Hashanim" but before beginning "Teka Beshofar," early authorities are at odds regarding what should be done. According to Ra'avyah (Rabbi Eliezer ben Yoel HaLevi), at this point one is still considered to be in the "Birkat Hashanim" blessing, and therefore says "Veten Tal Umatar Livracha" and continues on to "Teka BaShofar." According to Rabbenu Yona, on the other hand, at this point it is as if one has already begun the "Teka BaShofar" blessing and therefore he can correct himself by adding the request for rain in the "Shomea Tefillah" blessing.
The Ben Ish Chai and Kaf HaChaim rule like Ra'avyah, while the Mishnah Berurah rules like Rabbenu Yonah. We follow the opinion of the Ben Ish Chai, the reason being that one is liable to forget to request rain again in "Shomea Tefilla."
2. If a person realizes his mistake after beginning "Teka Bashofar," he need not go back; rather, he requests rain in the "Shomea Tefilla" blessing.
3. If a person does not realize his omission until after the "Shomea Tefilla" blessing, before "Retze," he must request rain at this point.
4. If a person only realizes his omission after having begun "Retze," he must return to "Birkat Hashanim," request rain, and then continue his prayer from there.
5. If he realizes his mistake after saying "yihyu leratzon" just before "Oseh Shalom" at the end of the "Shemoneh Esreh" prayer, he must go back to the beginning of the "Shemoneh Esreh" prayer (Ben Ish Chai, BeShalach 18; and see Kol Eliyahu Prayer Book 208-209). Repeating Ninety Times
Where a person is not sure if he said "Barchenu" or "Barech Alenu" during the thirty days following 7 Marcheshvan, he must return as explained above. In order to avoid such uncertainty, it is advisable to say "Rofeh Choleh Amo Yisrael, Barech Alenu" (according to the Sephardi version of prayer) ninety times. Once this has been done, if there is any uncertainly, we can assume that he said "Barech Alenu" and therefore need not return.
The Ashkenazi version of "Birkat Hashanim" begins no differently in the winter than in the summer. The only difference is that in the summer one inserts "Veten Beracha" and in the winter one inserts "Veten Tal Umatar Livracha." Therefore, in order to avoid uncertainty, one must repeat "Ve'et Kol Minei Tevuatah Letova, Veten Tal Umatar Livracha..." ninety times.
Likewise, it is important to realize that if thirty days have passed since the previous "Birkat Halevana" ("Blessing of the New Moon") One must read this blessing from the prayer book. In some places, the words of the "Birkat Halevana" are painted on the wall of the synagogue in large letters, and in other places sheets containing the prayer are handed out. If a person does not have a copy of this prayer, he should recite it along with the prayer leader word for word in order to avoid making a mistake.