Editing Snow

Snow is a form of precipitation consisting of crystalline and airy ice flakes, relatively large, that fall from clouds to the ground.

== Snow in Halacha and Chabad Teachings ==
Snow is mentioned in Tehillim as a source for contemplating the greatness of Hashem Yisborach: "Fire and hail, snow and vapor, stormy wind fulfilling His word."

The halachic approach to snow varies. In the laws of tumah and tahara, snow is considered neither a liquid nor a food. In the laws of mikvah, snow has the status of water, and one could theoretically immerse in it if not for the issue that it lacks the name "mikvah" when frozen and doesn't have the form of water. However, it can be melted to make a mikvah, and we have testimonies from our Rebbeim about this.

One such testimony comes from a complex question brought before the Tzemach Tzedek regarding a mikvah where concerns arose about its kashrus. There was a possibility it had the status of "mikvah shehimshichuha bekulah," meaning most of its waters were created through hamshachah (making drawn water kosher by flowing it on the ground three tefachim before entering the mikvah). Some hold this invalidates the mikvah unless most of its waters are kosher water, with only a minority being drawn water that underwent hamshachah. The question arose how to make a new mikvah in a place without rain, or in a covered location where rain cannot fall directly without using vessels that would make it drawn water.

== The Tzemach Tzedek's Ruling ==
The Tzemach Tzedek clarifies the topic of making a mikvah from snow or ice, ruling that forty seah of snow or ice should be placed in the mikvah. Many Rishonim wrote that even if one made an entire mikvah from snow, frost, or hail brought in vessels, it's kosher. However, the Beis Yosef writes that from the Rambam it appears only snow can be used initially for a mikvah, but not ice. The Tzemach Tzedek rules that since most Rishonim disagree with this, ice can be added to mikvah water when snow isn't available, thereby making the mikvah kosher by ensuring most of its water is completely kosher.

However, the Tzemach Tzedek qualifies this by ruling that as soon as it's possible to bring enough snow to the mikvah that when melted would equal forty seah, this should be done, as making a mikvah from snow is accepted by all Rishonim. The snow should be placed in the mikvah pit and melted by the mikvah's own heat, not by adding hot water which would invalidate the mikvah.

== The Alter Rebbe's Instruction ==
As support for his words, the Tzemach Tzedek brings that the Alter Rebbe gave similar instruction to make a mikvah by first removing the water from the mikvah and bringing snow to put into the empty mikvah. Afterwards, they would heat the bathhouse until the snow melted and became forty seah of water.

However, there is a distinction between making a mikvah with snow versus ice; when making a mikvah with ice, there's no need to empty the mikvah, since ice is a controversial permissibility when used independently and not as an addition to an existing mikvah. According to the Rambam it's invalid, so it's better to throw it into the mikvah with the previous water of questionable kashrus, even though others hold this isn't done properly, since either way the mikvah isn't completely kosher according to all opinions, and the sides of doubt are equal. In contrast, before adding snow to the mikvah, which makes it kosher according to all Rishonim, the mikvah water must be completely emptied, and the snow placed into the empty pit.