Because of the (warm) Portuguese mainland cooling off during the night, and this happening considerably faster than the ocean during night time, the airmass above the mainland moves seaward because of the difference in air pressure caused by this phenomenon. Sailors know this mechanism as land breeze. Land breeze is the opposite of the sea breeze we all experience at the beach during the day in summertime when fresh air moves to landward.

When I arrived my first day, here at the west-coast of Portugal, I was astonished by the local climate. When I woke up at 6 o'clock for the morning prayer, I was expecting, as usual in northern Europe, to have my teeth together, trying to survive what should normally be the coldest period of the day, around dawn. I was astonished to feel warm air entering the windows and I could not believe the feel of its comfort. I took my thermometer and it showed 24 degrees Celsius!

That was two weeks ago and this hot land breeze coming in through the windows repeated itself many times. What a nice climate! Hot days and warm air coming in at night :)

Today was another day.

This warm land breeze passing over my boat at night finds itself above the ocean close to shore. When this air mass starts cooling off above the relatively cold ocean, the temperature change of this air is an obvious result. If dew point is passed, this air mass looses its capacity to hold the same amount of moist. The result of this is the forming of fog. This advection fog, occurring 10% of the times here at the west-coast of Portugal, is the most hated thing for seaman because sight near the shore is reduced to almost zero.

Today was such a day and there was virtually no wind to blow the fog to landward. I occasionally saw the sun and some junior sailors trying to make the best out of this foggy day.

I spent the day eating and reading. Since I'm now on the Iberian peninsula, this was an excellent moment to continue reading my book about the history of this piece of the earth. Islam has been dominant for 500 years here in Portugal.

I can feel this in the behaviour of Portuguese people. They still posses a little piece of the illumination which has been removed in the 17th century by the horrors of the Spanish inquisition when the many Muslims of the Iberian peninsula faced two options: convert to Christianity or be killed! Sadly, most Spanish and Portuguese people today don't know that their ancestors were probably Muslims.

To end this update, I would like to share a paragraph I was reading today:

When Cordoba was at the height of its flowering there were over 200,000 houses in the city, along with six hundred mosques, nine hundred public baths, fifty hospitals and several large markets which catered for all branches of trade and commerce including 15,000 weavers. You could walk through her streets for ten miles in one direction at night, and always have the lights of lamps to guide your way. Seven hundred years later this would be an innovation in London or Paris, as would paved streets.