Shemini Atzeret literally means “the assembly of the eighth (day).” Tishri 22, the day after the seventh day of Sukkot, is the holiday Shemini Atzeret. In Israel, Shemini Atzeret is also the holiday of Simchat Torah. Outside of Israel, where extra days of holidays are held, only the second day of Shemini Atzeret is Simchat Torah: Shemini Atzeret is Tishri 22 and 23, while Simchat Torah is Tishri 23.
Shemini Atzeret is mentioned in the Bible, but its exact function is unclear. In Second Temple times, it appears to have been a day devoted to the ritual cleansing of the altar in the Temple. With the destruction of the Temple in 70 CE, this function of the day became obsolete. It marks the beginning of the rainy season in Israel and, therefore includes the year’s first prayer for rain. [www.myjewishlearning.com]
This year the Yoreh (the 1st hard rain of the season) came just two days after Shemini Atzeret. An amazingly accurate timing when considering that there was no rain in Israel for the previous six months and there was no sign that the Yoreh is coming until after Shemini Atzeret.
Simchat Torah (Rejoicing of the Torah) is a Jewish holiday that celebrates and marks the conclusion of the annual cycle of public Torah readings, and the beginning of a new cycle. The main celebration of Simchat Torah takes place in the synagogue during evening and morning services. In Orthodox as well as many Conservative congregations, this is the only time of year on which the Torah scrolls are taken out of the ark and read at night. In the morning, the last parashah of Deuteronomy and the first parashah of Genesis are read in the synagogue. On each occasion, when the ark is opened, the worshippers leave their seats to dance and sing with the Torah scrolls in a joyous celebration that can last for several hours. [Wikipedia]
Simchat Torah celebration on the boardwalk in the Israeli mediterranean city Netanya