Drake Passage is one of the most turbulent sea routes. In that sense it is an extraordinary region, but the truth is that the seas of the Southern Hemisphere have always been a source of trouble for sailors. Reason: their storm. Now we are a little closer to knowing why they are more intense in the south than in the north.
a stormy hemisphere.
A team of researchers from the Universities of Chicago and Washington has so far demonstrated a simple intuition that the Southern Hemisphere is windier than the North. in the study, published in the journal Proceedings of the National Academy of Science (PNAS) The researchers also calculated the size of the difference: 24%.
But measuring a phenomenon is only the first step when it comes to answering the question that matters most: why. The reason is related to the geography of our planet. Two-thirds of it is covered by water, but the ratio between landmass and ocean is not homogeneous.
Water covers more than 60% of the surface of the Northern Hemisphere, while in the case of the South they cover more than 80%. This in turn has two implications.
Mount: First Offender.
The first reason is on the ground and that is the mountain ranges. Irregularities in terrain affect storms because they hinder air circulation. This slows down the currents and hinders the formation of storms. In fact, the main storms in the Northern Hemisphere usually originate in the waters of the Atlantic and Pacific Oceans as hurricanes and cyclones.
From the Rockies to the Himalayas through the Atlas, the Alps, and many other formations, the Northern Hemisphere is filled with mountains and mountains on all continents. On the other hand, in the Southern Hemisphere, only the Andes and the South African Plateau stand out.
Ocean and its currents.
The second reason is related to water and that is that like the wind, the sea also has its own currents. These currents carry millions of tons of water throughout the oceans.
Researchers compare it to a power conveyor belt, as these currents carry warm water from the tropics and carry it toward cooler regions. The warmer, less dense water continues to circulate on the surface until it reaches the poles. It is then that it cools and becomes darker to resume its path.
Most of this circulation takes place in the southern oceans. In fact, although the Gulf Stream reaches the North Atlantic, currents such as the Transpolar Current (which encircles Antarctica) circulate exclusively through the South Pole. This current is precisely what makes the Drake Passage so violent.
To understand how orography and ocean circulation affect the occurrence of storms, the team of researchers used computer simulations. He made a model of the Earth in which he could change these parameters.
Thus, for example, they found that “smoothing out” mountain ranges meant reducing the difference between storms in the two hemispheres. On the other hand, when they eliminated the effect of ocean currents, they were able to make the other half of the difference disappear.
a growing gap.
Analyzing storms occurring on either side of the equator, the team of researchers also found that this difference had been increasing since the 1980s. Notably, while the Southern Hemisphere was getting stormier, the North remained stable.
The reason for this is the change in ocean currents. In addition to the Southern Hemisphere being more exposed to these currents, the effect would have been offset by greater heat absorption in this region to the north, caused by Arctic melting.
Resolving the distribution of storms is a small step in our ability to better understand the complex systems that comprise weather and climate. This is not only important for creating more accurate climate models that allow us to better understand the world around us, but it can also help us make more accurate weather predictions so that even if we don’t get to the most extreme places in the world, Have to cross a dangerous strait, let’s do it as safely as possible.