East to west, you'll need rest

Some time ago, I came up with a little mnemonic to remember how direction of travel affects flight times:

East to west, you'll need rest. West to east, not in the least.

That's right, flying eastbound is faster than flying westbound along a similar route. For example, flying from California to New York takes about 5 hours, but flying from New York to California takes about 6 hours. The difference is not caused by Earth's rotation, but rather the jet streams.

#Science