output array elements in rows

Dear list,

I'm looking for a function to output the elements of my array column in
rows ? Let's say I have following table:

id = integer
nam= array char varying

id nam
1 {"nam1","nam2","nam3"}
2 {"n1","n2"}

I think there should be available a function to expand the elements of an
array of caractères into a set of rows ?

id nam
1 nam1
1 nam2
1 nam3
2 n1
2 n2

THANK YOU VERY MUCH FOR YOUR HELP