Space tsunamis have revealed the weak spots in Earth's invisible magnetic shield, highlighting the regions where dangerous solar storms can 'find a way through'.

According to researchers from the University of Oulu, Finland, the powerful bombardment of particles and energy known as solar wind doesn't pass over Earth evenly.

Instead, powerful waves form at the edge of Earth's protective magnetic field, causing the wash of energy to build up more strongly in some areas than others.

Scientists now say that the strongest activity forms in the winter hemisphere, which is facing away from the Sun.

Depending on the direction of the solar wind’s magnetic field, it is concentrated either on the dawn side or the dusk side of the planet.

That means countries with high latitudes like the UK, Canada, and Norway will be most at risk from solar storms between December and February.

Meanwhile, low-latitude nations such as New Zealand, Chile, and South Africa will be at risk in the austral winter between June and August.

It means these areas may be on the front line when powerful solar storms slam into Earth, threatening everything from navigation systems to electricity networks. 

Life on Earth as we know it is partly possible due to the magnetic shield known as the magnetosphere.

This powerful magnetic field is generated by swirling currents of molten metal deep within the planet, and helps to deflect the deadly stream of solar wind.

However, the outer edges of this layer are not sealed, and there is a constant interplay between the Earth's magnetic field and the magnetic currents in the solar wind.

These interactions help to drive solar weather, producing effects like the glowing aurora that can be seen at high latitudes.

But when solar flares or bursts of particles called 'coronal mass ejections' arrive, they can also cause powerful geomagnetic storms.

These storms are extremely dangerous for the planet's critical infrastructure, and extremely powerful outbursts can disrupt satellites, radio communications, and even cause blackouts.

Part of what makes the effects of solar storms so hard to predict is that they don't pass over Earth evenly but scientists haven't been sure exactly why.

Since satellites only rarely pass through the most active areas of the magnetosphere, direct observational data is rare.

However, in this new paper, published in Geophysical Research Letters, researchers examined these interactions using a computer model of the entire magnetosphere.

In particular, they focused on waves that form when the fast-moving solar wind brushes up against the edge of the magnetic field.

These are known as Kelvin-Helmholtz waves, and they can be found all around Earth and the solar system.

You can see Kelvin-Helmholtz waves in wind-whipped clouds, swirling river waters, and even in the clouds of Saturn.

Lead author Dr Lauri Holappa, of the University of Oulu, says: 'In 2020, when I was visiting NASA as a postdoctoral researcher, I noticed unusual simulation images of the magnetosphere.

'I later realised that they showed Kelvin–Helmholtz waves at the edge of the magnetosphere, and that the different behaviour of the waves on different sides was part of the same phenomenon.'

Dr Holappa and his co-authors discovered that these waves don't form neat mirror images as they pass around Earth.

Instead, they appear asymmetrically on either side of the magnetosphere, with the more active areas putting more pressure on Earth's defensive barrier.

Dr Holappa compares this to what happens when a powerful wave meets a breakwater; it doesn't divide itself evenly but rather whips around one side more strongly.

In the case of Earth, this happens because the solar wind's magnetic field is unevenly draped over the magnetosphere.

'Asymmetries in the wave motion at the edge of the magnetic field have been observed before, but now we were able to show how they arise,' says Dr Holappa.

These findings have important implications for understanding how space weather forms at the edge of the magnetosphere, and how that process is affected by the seasons.

The researchers say this should help to improve the accuracy of space weather forecasts in the future.

If space agencies have more advanced warning of a powerful geomagnetic storm, they can take measures to protect satellites and power grids from damaging effects.

So, knowing exactly where and when the worst effects will be felt could be critical to keeping the world's satnavs, messaging services and internet connections up and running.