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  • Morroco, from Salares
    Morroco, from Salares
  • digitally enhanced
    digitally enhanced
  • and seen from Competa
    and seen from Competa
  • North African mountains
    North African mountains
  • pressure chart, 17/01/10
    pressure chart, 17/01/10
  • seen on  21 Dec 2011
    seen on 21 Dec 2011

Mirage

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A popular topic of discussion here in Southern Spain is whether North Africa is visible from Málaga province, or not. Some theorists claim it's not possible, whereas locals disagree because they have occasionally been able to see North African mountains across the Mediterranean.

The coastal mountains of Morocco, the Rif mountains, have an average height of around 600 meters, much the same as the populated parts of the coastal mountains of Málaga. They are part of the same geological formation as those in Southern Spain, and are not part of the Atlas mountains. A quick search on Google, or use of the calculator below, will tell you that from a height of 600m, you could see another peak of a similar height at a distance of up to 175km away. The average distance to the Morrocan Rif mountains is 210km, so in theory, they are too far away to be visible, being over the horizon. However, there are two high peaks; Jebel-El-Kelaâ at 1616m and Jebel Tidiquin at 2448 m and the tops of these should be just visible from a height of 600m here in Málaga province. When the North African mountains are occasionally visible, it is a whole range that comes into view, not just a couple of high peaks. They can also been from the coast here, which is theoretically impossible under normal conditions.

 

Most people will be familiar with Hollywood's desert mirage of a shimmering blue lake in the distance. This type of mirage is caused when light coming down from the sky is bent upwards such that the blue sky appears to be on the ground. This bending of light is caused by the difference in air temperature between the hot desert surface & the cooler air above. This is the same effect as the heat shimmer on a very hot road surface in high summer, although on a much grander scale. The bending of light is known as refraction; the same process that makes a stick dipped into a pool appear bent.

 

There is another type of mirage where the opposite effect occurs if the air temperature is cool on the ground and rises with altitude; instead of light being bent upwards away from the earth's surface, it is bent in downwards; the opposite direction. Rising temperature with altitude is an unusual condition; it's normally cooler in the mountains than on the coast. Very occasionally, the air temperature does rise with altitude & this is the condition required for the type of mirage that can bring the Morrocan Rif mountains into view. This is known as a superior mirage, and the atmospheric condition is called a temperature inversion. If this temperature inversion is present across the entire Mediterranean between Andalucía & Morroco, then conditions are right for the mirage to occur. Conditions were right on the afternoon of 17th January 2010 when the Morrocan mountains were clearly visible.

 

On this day, warm air was descending from high altitudes, trapping cooler air beneath it. In the afternoon, the temperature on the coast was 17ºC, but 21ºC at 600m height in Salares. Humidity was also high at low levels (70-80%), but low higher up, which also aids refraction. There was very little wind, which would have stirred up the temperature inversion. All these things combined to bring the mirage into view.

 

Can you see a distant peak? - use this calculator:

 

Horizon calculator