on the nether side

In Summer or Harvest, when the Wind has been South two or three Days, and it grows very hot, and you see Clouds rise with great white Tops like Towers, as if one were upon the Top of another, and joined together with black on the nether Side, there will be Thunder and Rain suddenly.

Time and time, When all Earth's light has lain on the nether side, And yapping midnight winds have leapt on the roofs, And raised for him an evil harlequinade Of national disasters in long train, That tortured him with harrowing grimace, Now I would leave him to pass out in peace, And seek the silence unperturbedly.