Fata morgana in Huvudskär - 18 - 20 May 2018

Huvudskär is located 31 miles from Stockholm downtown, therefore easily accessible for a weekend.  It is usually the first ride of the year, even though, this year, with the summer starting early May, we have been cruising around to Sandhamn and Utö earlier this year.

Huvudskär, Belisama moored at the Svenskakryssar association buoy.

The picture below is taken few minutes after mooring, early evening. As we are entering the period of the longest days, you should imagine the sun setting along a diagonal line that will probably go to the intersection of the mast and the horizon. Still long way to go!

The following morning, bright sun again, but very cold air breeze coming from the south west, meaning the open Baltic sea. I depart around 10, and go out through the north sound of the skär before turning north west towards Utö. On the picture below, you can see the main island of Huvudskär with its lighthouse. What strikes me immediately is the darker band over the horizon on the right area where the elevation is the lowest. It could look just like a cloud line over the horizon, but it is not. It is again one of the Morgan le Fay tricks...  

Passing along the tip of the island, it becomes obvious that the band on the horizon extends very broadly. This is in fact a fata morgana, a mirage created when there is an inversion, a layer of cold air stuck at the surface of the sea, above which there is a duct of warmer air, which gets colder again at a higher altitude. These are the conditions for this phenomenon to appear, resulting in a stack one to several layers of inverted images, reflected at the interface of the air layers of different temperatures. I would certainly not have noticed anything particular here before making some reading last year when we encountered such fata morgana on 27 May 2017 in pretty much the same area. The only difference then was that there was a cargo passing along, which was reflected in several stacked inverted copies.

In fact, last year we saw the same persons, at the same time and place saw the same phenomenon. It cannot be a coincidence for an epidemiologist. This would seem to indicate May is the period, given the still cold night, prone to inversion over the sea area in quite anticyclonic weather as we have been experiencing now for 3 weeks.

The picture below shows two layers. It is a pity that there are no boats passing by on this Sunday morning.

This is looking north, towards the coast of Utö.

We can see the line of the vegetation appearing 5 times at the centre, up first, then down, up again, down and finally up.

Fascinating as well was that the temperature of the air breeze increased very significantly as I turned around downwind from Utö. The cold air of the sea got heated by its passage over the island.

This is not a fata morgana. Unfortunately, the Tre Kronor av Stockholm did not pass by during the morning before the inversion was gone. Same boat that we already met on our way back from Sandhamn in a previous post. There was 8 to 10 m/s wind, sideways for her, and she was going 4.9 knots on the AIS.

The Three Kronor av Stockholm, on her way to Nyköping

I forgot to mention the new pairs of socks for the Belisama fenders, home made. It took a full day for eight of them. I am proud of how nice they look. But for how long? Noticed the logo? And it was quite a struggle to inflate back the fenders after pushing them through the socks! On my next trip to France, I should get the 2€ adaptor allowing to inflate and lock without having to disconnect the pump.