A nonstop flight from San Francisco to New York takes about 5 hours and 30 minutes. The same flight going in the opposite direction, from New York and ending in San Francisco, will take almost one hour longer. Why does flying west take longer, especially given that the westward-bound plane would be going opposite the earth's eastward spin? That is, if earth is spinning east, why does it take longer to go west?
The earth's rotation does play a role in slowing your westward flights, but not in the way that you would think. As it turns out, the earth's rotation affects high altitude winds known as the jet stream. As the earth spins towards the east, it pulls everything with it, causing jet streams that blow from the west to the east. Like the physics on the ground, objects that move with the jet stream current travel faster than objects that travel against the jet stream current. So, whether you're at sea level or at the cruising altitude of a Boeing 757, it all comes down to tailwinds and headwinds.
