Ten verses. The frogs, silent for a year like vow-keeping Brahmans, lift the voice Parjanya has inspired when the floods of heaven fall on them in the dry pool bed. They greet each other like son and father, repeat each other like pupil and teacher, differ in voice (cow-bellow, goat-bleat) and colour (green, spotted) but share one name. They gather round the pool like Brahmans round the full vessel at the Atiratra rite on the first day of the rains, and like sweating Adhvaryus come out with none hidden. The poet asks them for cows in hundreds and long life.
When the monsoon is late, Assamese villages hold a wedding for two frogs. An Assamese verse has farmers ask the clouds why there is no rain; the clouds answer that there is none until the frogs croak. A male and a female frog are caught, washed, dressed as groom and bride, seated on a platform and joined with a red thread; a priest or elder performs the rites and prays to the rain god; vermilion is put on the bride. They are released in a pond; if they stay together rain is expected.
What is different here:
A living folk rite, not a hymn. The frogs must be made happy before rain will come; the god named is Varuna, not Parjanya. Similar rites are reported as Mandooka Parinaya and Banger Biye elsewhere.
The rain charm repeats the first verse of the frog hymn and adds direct orders: let the speckled-armed frogs send out their voices along the brooks; let the female frog speak a welcome, greet the rain and swim in the middle of the lake with four feet spread.
What is different here:
The frogs are told to call so that rain will fall; in the Rigveda the rain comes first and they answer.
Sources: Hymns of the Rigveda, tr. R. T. H. Griffith (1896), hymns read for the Vedic layer; Wikipedia: Bhekuli Biya; Hymns of the Atharva-Veda, tr. R. T. H. Griffith (1895)