My earliest childhood memory is of the swaying limbs of Golden Delicious apple trees. Rows of them stood next to a dirt road that separated our orchard from the front yard.
The Kentucky summer sky hung hot behind those high twigs, their leaves leathery green on top, soft as down underneath.
Frank Browning,“Sweet Temptation,” Reader’s Digest
Why, both down and underneath and not one of them; for example, underneath?
Is it emphasis? Sentence rhythm if you will?