Комментарий к Берешит 8:13

בראשׂון IN THE FIRST MONTH — According to R. Eliezer this would be Tishri, and according to R. Joshua Nisan (Rosh Hashanah 11b).

ויסר נח את מכסה התבה, he had thought that the earth had already dried out completely only to find

[Began] to dry. It was still like mud, dry on the surface but soft underneath. Noach knew that Hashem would tell them when it was safe to go out.

ויהי באחת ושש מאות שנה בראשון באחד לחודש. It was inthe 601st year (of Noach’s life) on the first day of the first month; even a single day of a new year is referred to as the year just commencing.” (Compare Talmud Rosh Hashanah 10) A different explanation of the significance of this statement: in the 600th year of Noach’s life in the month of Iyar on the 17th of the month the deluge had commenced, and the rain lasted for 40 days and 40 nights, so that the rains ceased by the 28th day of Sivan. According to this interpretation the first month of the year is the month of Nissan. All the other months follow the same patterns according to the solar calendar. Each month is considered as having thirty days.

חרבו [THE WATERS] DRIED UP — It (the earth) had become like clay, for now its surface had become somewhat hardened.

והנה חרבה פני האדמה, that whereas there was a thin layer of earth above the water, the earth had not yet dried out thoroughly.