This WeatherBlog was written a little earlier than usual due to vacation plans and appears here with a time delay, so that we tend to deal with things that are not so current. From today's perspective (Monday), the weather is looking increasingly April-like in the near future, with slightly lower temperatures (as would be expected in April) and occasional, sometimes heavier, thundery precipitation. Note: The thunderstorm season is open!
Let's return to the Saharan dust that has already been mentioned several times, as it has been really impressive recently. The weather forecasts for last Friday in particular, and in some cases those for the weekend, were too positive, as no weather model takes the influence of dust in the air into account. The models saw sunshine and hardly any clouds, but a dense cirrus screen obscured the sun and the weather was gray and unattractive. The sand itself does not darken the sun, and at lower concentrations it is even known to make for particularly colorful sunsets. However, the many condensation nuclei in the air form a dense cloud cover that would not exist without the sand. This cloud cover extends to great heights and is optically very thick, which means that very little solar radiation penetrates it.
But that's not all! The sand continues to mix in. We know that the air cools down more on clear nights than when it is overcast. This is primarily due to the fact that the ground emits heat radiation and only really gets rid of it in clear conditions. Through contact with the cold ground, the air near the ground also cools down. Left to itself, it would cool down much less, hence the popular inversions on the ground in winter (only the air close to the cold ground cools down.)
If you now have more dust and sand on the upper edge of the sandy cloud canopy, it behaves similarly to the ground and radiates heat into space. This lowers the temperature at the top of the cloud. This in turn increases the lability and leads to lifting effects, sometimes even thunderstorms.
Further information here and here .
Since the WeatherBlog is under a bit of stress and should have packed up by now, this week we are merely presenting readers with a few links for voluntary self-study:
Will there be a Super El Nino next year?
Still extreme drought in California
Information on the current snow situation in Norway
Nice, high-resolution satellite image of Norway
The WeatherBlog will be back one last time in this winter that is coming to an end towards the end of April and will then be gone for a short time.
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