In each leap year one more month is added to twelve months. It's called Adar Beit and means one more, second additional month of Adar. Besides in fact it becomes thirteenth month of the year, the ordinal number of the month and its constellation doesn't change. Second Adar should also be called twelveth month of the year.

Adar is the last, twelveth one among the months of the year, if counting them from the spring month of Nisan, as Biblical law requires. The constellation of Pisces corresponds to Adar as far as it is exactly on this month that breeding for most fish in rivers and lakes takes place.

Shevat is eleventh month of the year according to Biblical calendar. The constellation of Aquarius or vessel - if translated literally from Biblical language - corresponds to the month of Shevat. As far as most of rains usually end by the month of Shevat, reservoirs are full with water this time and the dip-buckets are abound in water.

Tevet is the tenth month of Biblical calendar. The constellation of the month of Tevet is Capricorn or kid - if translating literally from Biblical language. It is exactly on this month that herds of goats are back to winter pastures. There should be underlined there are no joyful dates in Tevet except for a few last days of Hanuka.

Kislev is the ninth month of Biblical calendar. The constellation corresponding to the month is Sagittarius or bow, rainbow - if translated literally from Biblical language. As far as Kislev has both many sunny and rainy days, it is especially often that the rainbow appears on the sky during the month.

Cheshvan is the eighth month of Biblical calendar. It is a special month. In TaNaCh it's called Bul (fading - Biblical language translation) as far as grass is fading in meadows when the month comes and the cattle starts being feeded with hay prepared in advance (RASHI's comment).

Tora always calls Tishrei a seventh month, meaning it is the seventh one if counting months from Nisan as Biblical law requires. Biblical sources state: "The favourable lot is meant for every seventh from on high".

Elul is the sixth month of Biblical calendar. The constellation of the month is Virgo. It is the symbol of the purity and modesty because Elul is month of repentance and return to Hashem. Virgo symbolizes the permanent aspiration for perfection, self-purification and special inner beauty.

The month of Av is the fifth month of Biblical calendar. The First and the Second Temple was destructed on this month. There exists an opinion that name of month can be read and interpreted as the abbreviation of the words Edom and Bavel what means names of two empires which destructed both Temples.

Tammuz is the fourth month of the year according to Biblical calendar. Tammuz name has Babylonian origin. The very Tammuz word is name of the familiar pagan cult and the words of prophet Yechezkiel confirm it (Yechezkiel 8:14): "And behold there the women were sitting, making the Tammuz weep".