What is the proper way to pronounce the word geshem?

The verse of Mashiv Haruach is added to the second brocha of Shemoneh Esrei from Musaf on Shemini Atzeres until the first day of Pesach. The poskim disagree on whether the word geshem should be enunciated with a segol beneath the gimel (geshem) or whether it should be pronounced with a kamatz (gashem). From the first day of Pesach, Sefardic communities and all communities in Eretz Yisroel say Morid Hatal, while Ashkenazic communities do not have any additions throughout the summer. A resident of Chutz L’Aretz who is visiting Eretz Yisroel need not change his minhag unless he moves there permanently. In the reverse situation, an Israeli visitor should maintain his own custom unless he serves as chazan. If he relocates to Chutz L’Aretz, he may change his custom.

סי' קי"ד ס"א ג' ביאורים ומוספים דרשו 3, 5

Why is it important to announce that people should begin saying Mashiv Haruach?

Chazal preferred that entire congregations should begin saying Mashiv Haruach at the same time. Therefore, they instituted that the one may only begin saying Mashiv Haruach after it is announced in shul to do so. If the announcement is made before the quiet Shemoneh Esrei, the tzibur may begin to say it during the private Shemoneh Esrei. Otherwise, the chazan begins by saying it during Chazoras Hashatz. This serves as the announcement, and the tzibur begins adding it at Mincha. If a member of the tzibur erroneously says Mashiv Haruach aloud during his private Shemoneh Esrei, some poskim consider that an announcement, and the people who hear him may add it into their own tefillos. In communities where Tefillas Geshem is recited before the quiet Shemoneh Esrei, it serves as the announcement to begin Mashiv Haruach.

ס"ב ס"ק ד' ביה"ל ד"ה אסור ביאורים ומוספים דרשו 8

Which tefilla is the last Shemoneh Esrei in which Mashiv Haruach is said?

Just as Mashiv Haruach cannot begin without an announcement, it cannot end without one. In communities that say Morid Hatal, an announcement is made that people should begin saying Morid Hatal. It can then be deduced that the tzibur should stop saying Mashiv Haruach. In communities that do not say Morid Hatal, the only alternative would be an announcement that people should stop saying Mashiv Haruach. This would be inappropriate, however, since it appears as if we are asking for a cessation of the brocha of rain. Instead, the tzibur and chazan still say Mashiv Haruach through the quiet Shemoneh Esrei of Musaf on the first day of Pesach. The chazan’s omission of it during Chazoras Hashatz is considered an announcement, and the tzibur then omits it at Mincha.

ס"ק ג'

• Chazal instituted that a person should bow at the beginning and end of the brochos of Avos and Hodayah. One who decides on his own to bow at the beginning and end of other brochos should be instructed to abstain from doing so. Bowing more than necessary seems haughty. In addition, a person who adds stringencies where they are unnecessary may come to be lenient when he is truly obligated to bow.

• Some Achronim rule that a person may not bow at the beginning or end of any brocha, even if it is not in the middle of Shemoneh Esrei. Therefore, they rule that a person should not bow at the beginning or end of Birchos HaTorah before Kriyas HaTorah. Other Achronim seem to say that the prohibition against bowing during brochos only applies to Shemoneh Esrei.

• If a non-Jew who is carrying or wearing an idol or other form of avodah zorah passes by a Jew who is at a point in davening where he is supposed to bow, the Jew should not bow. Even though he does not have nefarious intentions, it appears as if he is bowing to avodah zorah.

• When does a person who is davening on his own say Mashiv Haruach?

• Is it necessary to repeat Shemoneh Esrei if Mashiv Haruach was omitted?

• Is it necessary to repeat Shemoneh Esrei if Mashiv Haruach was said in the summer?