Shady side means the north (left) side of the plane when going west to east within North America; the south (right) side when going from east to west (the sun is over the equator). In other words, a daytime RT from LAX-IAD-LAX is POSH (Port Out Starboard Home), even in Y. Flying north-south routes, in the AM on the west side, and in the PM on the east side.