Question:
I often see strange swirling systems that are in the Northern Pacific Ocean by Alaska. I was never told anything about the storms and I could never really find an answer to what they are on the internet. They remind me of an odd hurricane in the way that they circulate and I was curious to what they are. The link attached has a screenshot of what I’m talking about.
Answer:
These spinning storms in the Northern Hemisphere are called polar cyclones or polar lows. They spin counterclockwise because of the Coriolis force, which causes moving air to curve due to Earth’s rotation.
What is the Coriolis Force?
Imagine you’re standing on a spinning merry-go-round. If you try to throw a ball straight across to your friend on the other side, the ball seems to curve away from your target. Why? Because as you’re both spinning, the motion of the merry-go-round affects the path of the ball.
Earth acts like a giant, spinning merry-go-round. As the Earth rotates, any moving object, like air or water, gets pushed or curved. This “push” is what we call the Coriolis force. It’s not an actual force pushing on the air – it’s more like a trick of perspective because of Earth’s spin.
Coriolis Force and Weather Systems
In large-scale wind patterns on Earth (see the Polar Cell on that page for the area where polar lows form), the Coriolis force makes air move in a curve rather than a straight line. In the Northern Hemisphere, this force makes air curve to the right, while in the Southern Hemisphere, it makes air curve to the left. The effect is weakest near the equator and stronger as you move toward the poles.
The Coriolis force comes into play with polar lows because it makes the air flow around a low-pressure area in a circular pattern. In the Northern Hemisphere, this air moves counterclockwise around the low-pressure area, creating a spinning motion.
A polar cyclone, sometimes called an “Arctic hurricane,” gets its energy from heat transferred from the ocean to the atmosphere. When the warm ocean air meets the cold polar air, the warmer air rises, and moisture in the air condenses into clouds, releasing extra energy (called latent heat). This helps the storm grow stronger (lower pressure = stronger).
Polar cyclones are tricky to predict because they form fast – often within just 24 hours. They usually appear over Arctic or Antarctic seas during winter in each hemisphere: October to April in the Northern Hemisphere and April to October in the Southern Hemisphere.
