kitesurfing blog Mallorca -winds in our country
Air weighs … and so does atmospheric pressure. A cubic meter, by instance, an space of 1mx1mx1m of dry air at 20ºC and at sea level weighs 1.205 kilograms.
Fortunately we are accustomed to bear over our shoulders a weight of 20,000 kg, without any harm because of it, and, this happens because of the pressure exerted by the column of air of 300 km of height on top of us. We don’t notice this because we do not only receive this air pressure from above, but from below and even from within, getting it all balanced in that way.
Cold air weighs more than warm air and moist air more than dry air. This greater weight translates into higher atmospheric pressure, which is physically defined as the weight exerted by that column of air per unit area.
It is a magnitude that helps us to understand the movements of masses of air in a much more graphical way than for example temperature or humidity.
I propose a pair of mental associations that will help us understand the maps of time. An High Pressure Area is a kind of “inverted spring”.
Thus in the High Pressure Areas we have a column of air that weighs quite a bit and slowly expels part of that air at its base, while a Low Pressure Area more closely resembles an “inverted sink”, this low pressure center absorbs the air to make it rise as a sort of chimney. All that implies descent of air equals tranquility, whereas all the air ascent favors bad weather.
Thus among the various layers of the atmosphere there are important air movements that conditions the weather.
The differences in pressure
Air flows from the High to the Low Pressure Areas. The more pressure difference, the more flow we will have, and therefore, stronger wind. The high pressures are difficult to move and often only leave narrow corridors so that these storms can circulate.
If the wind finds no physical obstacle on its path, for example when it travels over the ocean, simply, will have to overcome the obstacles of pressure, bordering the high pressure areas.
The Galician coasts and the Cantabrian coasts are often a good example of such winds effect, but when the wind arrives on land it is with obstacles, that makes it go up or channel between mountain ranges, as an example of it on the valley of Ebro river.
Here is a chart of maximum wind gusts recorded in Spain, record by communities according to a series of data extracted from AEMET (some series span from 1938 to 2016).
In addition, our latitude is affected by the Azores High Pressure Area. The northeast winds (trades) practically define the weather and the winds affecting the Canary Islands. Wind that it channels between this islands.
The High Pressure Area which has its center on the Azores islands, also favors the rising wind which is frequently channeled in the Sea of Alborán, and also having a closed and not excesively deep sea, as the Mediterranean Sea, this definitely has a great influence on the Balearic Islands and the whole Mediterranean basin.
It is expectable for any cloud front to end up generating a Low Pressure Area near the Gulf of Leon, which propels particularly intense northern winds to the north-east of Girona.
There is much more to talk about all this topic but the post is already long enough.
Unfortunately most of the data belong to capitals or airports and some strategic spots such as the Ampurdà or the peaks of the most notorious mountain systems are not displayed.
It is also interesting to take a look at the chart on the wind map on the first photo of this blog entry to confirm that the higher wind areas in Spain are in the northeastern coast of Galicia, the region of Ampurdà in Girona province coasts, in the Sea of Alborán, in the Strait of Gibraltar and on the islands, especially in the Canary Islands.
Winds in Spain – kitesurfing blog Mallorca