Here's what that means:

* Anticyclonic: The storm rotates in the opposite direction of Earth's cyclones (counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere).

* High-pressure: The air pressure at the center of the storm is higher than the surrounding air, causing the air to sink and rotate outward.

This high-pressure, rotating storm has been raging for at least 150 years and is likely much older.