Orkane is not what you think. They are not hurricanes. They are not typhoons. These are extratropical cyclones, technically called storm lows. We call them a winter storm.
They often attack Western and Central Europe. You remember the big ones. Vivian. Wiebke. Lothar. These names stuck because the losses were high.
But why do they happen? The name says it all. a winter storm. They mainly attack in winter. Sometimes even in autumn.
The reason is simple. temperature difference. Especially the gap between subtropical and polar regions.
The greater the drop in temperature, the greater the storm. In the cold season, the difference is more than double compared to summer.
Polar Front
Look at the Northern Hemisphere.
Cold air flows in from the polar regions. Coriolis forces push it west. Warm air comes from the south. Turn east with the same force.
There are certain boundaries where they intersect. Very sharp.
Here, the air masses pass through each other. The front is a wavy band that surrounds the Earth.
Warm air tends to creep over cold air. This creates a warm front. Cold polar air then pushes it back. Head south. It forces the warm air upwards along an oblique path.
The central pressure decreases.
This rotation creates a large low-pressure vortex. Cold air rushes in. The wind howls.
The strength of the wind is determined by the temperature difference between these fronts. The difference is most noticeable from autumn to winter.
Hurricane-force winds can blow across Central Europe.
Winter storms and tropical cyclones
Tropical cyclones are different.
They have no front line. They form over heated oceans. Their wind is fast.
But winter storms are another threat.
They create a wider storm field. They go further. They can travel 1,000 to 2,000 kilometers daily. This is a typical distance.
We live in a densely populated area. These storms extend over long distances. They pose a significant danger to populated areas.
That’s why we follow them closely. It’s not because they’re fast. But it’s big.
