Complex sentence: Wall clouds can be anywhere from a fraction of a mile (0.25 km) wide to over five miles (8 km) across, and in the Northern Hemisphere typically form at the south or southwest end of a supercell.
Split into simpler sentences: Wall clouds can be anywhere from a fraction of a mile (0.25 km) wide to over across. In the Northern Hemisphere wall clouds typically form at the south or southwest end of a supercell.