15 December: "The deep blue sky fascinates me!"

His blog is called "Alex extreme" because meteorologist Alexander Hildebrand is particularly enthusiastic about turbulent weather events. When he traveled to Antarctica aboard the HANSEATIC inspiration, he can explain why the Drake Passage can be challenging, at what altitude the weather forms over the continent, and why the air is so special.

Dear Alexander Hildebrand, your blog is called "Alex extreme" because the Earth's atmosphere fascinates you the most "thunderstorm-like and turbulent." When you boarded our HANSEATIC inspiration in December for a voyage to Antarctica, do you perhaps wish for calm seas for the Drake Passage after all?

Alexander Hildebrand: Crossing the Drake Passage to travel from South America to the Antarctic Peninsula is part of the great adventure of an Antarctic expedition. So I am inwardly prepared for calm seas and for storms. On calm sea days, however, the mood on deck is understandably somewhat better compared to storm days. I'm happy about that then, although fortunately I'm seaworthy.

Can you explain to our readers why the Drake Passage is such an idiosyncratic sea route?

The Drake Passage lies in the westerly wind zone, which stretches like a belt around Antarctica. It lies between the southern Arctic Circle and about the 50th parallel south. In this region, low-pressure areas move from west to east with great regularity. They cause rapidly changing weather and frequent storms. Due to the exposed position between Cape Horn and the Antarctic Peninsula, the storms have free course there and thus calm seas in the Drake Passage are the exception rather than the rule.

As a continent, Antarctica has an enormous, actually hardly imaginable size - it is about 30 percent larger than Europe. What do we know about Antarctica's climate?

In the middle of Antarctica, the ice is several kilometers thick. That's why the climate up in the interior of Antarctica is much colder than down at sea level; it's similar to our Alps. While the interior of Antarctica has average temperatures of around minus 30 degrees Celsius in summer, the summer around the Antarctic Peninsula ensures a mild 0 degrees. There, the climate is suitable for expeditions.

What relevance does the Antarctic climate have for all of us?

A stable climate on the continent is important for mankind, because its ice sheet is the largest freshwater reservoir on Earth. We don't want to drink the stored water, but warming of Antarctica has already led to the melting of large ice masses. Satellite measurements show that sea levels have already risen as a result. However, there is still a great deal of ice there, and we marvel at the frozen, white world quite intensively on site. But we experts also address the truth in our lectures on board - namely, that a lot has already changed in the climate of Antarctica.

What changes will we see in the next few years during our voyages to Antarctica?

The biggest changes are certainly to be expected in the extent of the glaciers and the ice shelves. Even the glaciers in the bays we visit in South Georgia have been receding in recent years. This was pointed out to me last time by the expedition leader, who has been going to the region much longer than I have. For my upcoming trip, I have prepared interesting data and descriptive graphics for this that I will show to the guests. It is hardly possible to see the climate changes during a single visit, but that is what we experts are on board for. We look at data series until a story pops up that we can tell the participants of the expedition.

Fascinating in Antarctica is an endless expanse, which is particularly impressive due to low-lying clouds. The whole weather event in Antarctica takes place at an altitude of about eight kilometers, in our latitudes it is about 13 kilometers. I also like to point out the fact that in Antarctica you are surrounded by water molecules in all three states of aggregation. Water vapor is invisible and everywhere, liquid water in the sea surrounds the ship, and water in its solid form floats around as an ice floe or lies as a glacier on the frozen continent.

The expedition voyages with the ships of Hapag-Lloyd Cruises take you to individual coastal sections of the Antarctic Peninsula. There you can experience some Arctic phenomena, such as the katabatic winds. What meteorological peculiarities will you explain to our guests?

"Catabatic" comes from the Greek and means "descent." These cold winds with downward motion components often arise suddenly and blow out of Antarctica at high speeds toward the coast. Their warm equivalent is the notorious Föhn in the Alps.

Your voyage with the HANSEATIC inspiration will also take you to the Weddell Sea, one of the marginal seas of Antarctica, from which enormous tabular icebergs break away again and again. What does it mean for you to experience such a region?

On land, I work as a meteorologist for a large weather company and for TV stations. When the famous iceberg A-68 broke loose from the Larsen Ice Shelf in 2017 and drifted northward through the Weddell Sea, I used satellite images to explain it to TV viewers. For me, it is particularly exciting to see, analyze, and explain other tabular icebergs on the ground in the Weddell Sea. So my job on land and my expert assignments for Hapag-Lloyd Cruises complement each other perfectly.

This is not your first expedition to Antarctica. What are you particularly looking forward to?

I'm looking forward to the clear air! Because Antarctica is isolated by the westerly wind zone, hardly any aerosols arrive there that are needed in the atmosphere for the formation of water droplets. Thus, there is little haze in Antarctica and no visible pollution in the atmosphere. In sunny weather, the sky is then deep blue, a fascinating sight!

Fotos: Roberts Johansons, Marco Ferchl, Archiv, privat, Interview: Dirk Lehmann