Why is wind shear consistently high in the South Atlantic?

The South Atlantic: Why Hurricanes Are Almost Unheard Of

Ever wondered why you almost never hear about hurricanes battering Brazil or South Africa? The South Atlantic Ocean is a bit of an oddball when it comes to tropical cyclones. Unlike the North Atlantic, where hurricane season is a yearly event, the South Atlantic is practically a hurricane-free zone. The big reason? Consistently high wind shear.

So, what exactly is wind shear? Think of it as the atmosphere’s way of messing with developing storms. It’s basically a change in wind speed or direction as you go higher up in the atmosphere. And in the South Atlantic, there’s a lot of it.

Now, hurricanes are essentially giant engines, fueled by warm ocean water. They need a calm, stable environment to get going and really ramp up. High wind shear throws a wrench into the whole process. Imagine trying to build a sandcastle in a wind tunnel – that’s what it’s like for a hurricane trying to form in the face of strong wind shear.

How does it do this? Well, for starters, it can rip a storm apart. Seriously. It tilts the storm’s structure, messing up the flow of air and making it much harder for the storm to organize itself. It also ventilates the heat and moisture that the storm needs to thrive, like opening all the windows in your house on a cold day. And finally, it prevents the storm from developing that warm core – the engine room, if you will – that’s essential for it to become a full-fledged hurricane.

Okay, so we know wind shear is bad news for hurricanes, but why is there so much of it in the South Atlantic? That’s where things get interesting. It’s a perfect storm (pun intended!) of several factors.

For one, the Southern Hemisphere tends to have bigger temperature differences than the Northern Hemisphere, which leads to higher wind shear. Then there’s the position of the Intertropical Convergence Zone (ITCZ), that band of clouds near the equator. In the South Atlantic, it sits closer to the equator, meaning the Coriolis force – the thing that gets storms spinning – is weaker.

And let’s not forget the lack of those helpful weather disturbances that often kickstart hurricanes in the North Atlantic. You know those tropical waves that come off Africa? They’re practically non-existent in the South Atlantic.

Of course, there’s always an exception to the rule. Remember Hurricane Catarina back in 2004? That was a real head-scratcher! It was the first recorded hurricane in the South Atlantic, and it formed because of some unusually favorable conditions, like slightly lower wind shear and warmer-than-usual waters. It was a reminder that nature can always surprise you.

Beyond wind shear, the South Atlantic also has cooler water temperatures than the North Atlantic, which makes it harder for storms to get going. And the Peru Current brings cold water up the coast of South America, further reducing the chances of hurricane formation.

So, for now, the South Atlantic remains a pretty safe place from hurricanes. But with climate change messing with everything, who knows what the future holds? Some scientists think that global warming could weaken the wind shear that protects the Southeast U.S. coast, and it’s not out of the question that we could see more activity in the South Atlantic down the line. We’ll just have to wait and see, and keep a close eye on those atmospheric and oceanic conditions. The ocean, as they say, is a mysterious mistress.