Many Dutch people claim to be much less affected by the heat when they are on holiday in the south of Europe than when they are at home. Can southern European heat really feel less hot? Two experts explain.
Humidity is the key word, explains meteorologist Raymond Klaassen of weather bureau Weerplaza. “In the south of Europe, the heat is often drier. This is due to the dry air, in which less water vapor is stored. This means that you are generally less bothered by the heat. Moisture in the air can cause it to become stuffy feels. That’s the big difference.”
“A very dry type of air has around 10 percent humidity,” says Klaassen. “Then the air is very dry. Above 55 percent, the air is less dry and you will notice it more and more. And above 70 percent and 75 percent, the air is already very humid. Around 90 percent to 100 percent, the air becomes even foggy.”
Humidity is highest in tropical regions. “There you are almost always above 80 percent and that feels super warm. That makes you more stuffy and makes you feel fuller. Moist air on your skin also has consequences. If the air is drier then it is easier to perspire, there it comes down to it. You don’t have a damp blanket hanging around you, so to speak.”
NU.nl climate reporter Rolf Schuttenhelm agrees. “The more humid the air, the less moisture evaporates from your skin – making it harder to cool down that skin. That makes it feel warmer.”
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Humidity depends on wind direction
Whether it feels clammy or dry mainly has to do with air currents. Southern air, coming from the Sahara, is often dry. Klaassen: “If we are faced with a southeasterly current, we also have dry air. Then it is better to endure it outside than when the warm air is full of water vapour.”
Schuttenhelm adds: “The humidity also depends on the air pressure and wind direction. We are often influenced by low-pressure areas of the Atlantic Ocean, which contain upward air currents that absorb a lot of moisture.”
Does a period of drought also affect the humidity? Klaassen says yes, but states that the influence of air supply is by far the greatest. “It mainly has to do with the place from where the air is supplied. You may have had a dry period, but if it is supplied by sea air then it is still humid.”
A southern supply can also be very dry in the Netherlands. “That is mainly air that comes from the Sahara. It still has to cross the Mediterranean Sea, but even then the air remains very dry, which makes it more manageable – even as far as the Netherlands.”
Still, not every southerly wind in the Netherlands is completely dry, says Schuttenhelm. “Something else often plays a role on our hottest summer days. Then we have a southerly wind, for example from Spain, which may have come from the Azores there – and therefore contains some moisture. Such a supply can actually lead to quite sultry temperatures in the Netherlands. This is because the air from Spain to the Netherlands cools down. Because colder air can contain less moisture than warmer air, the moisture percentage rises when it cools down. In Spain it is then 35 degrees and easy to handle, and in the Netherlands 30 degrees and sweltering .”
2023-07-13 19:05:11
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