system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does the East coast of the US have high humidity but the West coast doesnt?

Ive lived on both coasts for extensive periods of time and never understood why the humidity was high to the point of being unbearable on the east coast while the west coast doesnt have the same problem.
gpt
Both the Atlantic and Pacific oceans circulate clockwise above the equator. 

The water at the equator is heated more by the sun. Then that warm water flows northward. On the East Coast, it's the Gulf Stream Current. It carries heat northward, warming the air above it. Warm air can carry more moisture, so that's why the East Coast is humid.

On the West Coast, the clockwise circulation is bringing cold water down the coast from the Arctic region. This cold current cools the air above it. Cold air can carry less moisture, so the West Coast has lower humidity.