Watch out for the fog!

Fog represents one of the biggest problems for hikers, especially in the high mountains when, on snowy stretches, it can appear in sudden and unexpected banks. Fog reduces visibility: it can be particularly hazardous along trails, because it engulfs every useful visual point of reference. 
With fog you can easily get lost: you need to be very careful, and avoid going far or anywhere that you don't really know the territory.

The area where fog develops is generally restricted ("fog cover" or "fog bank"). 
Depending on its thickness, fog can reduce visibility to a few dozen metres, or even a few dozen centimetres.

This phenomenon is quite common in the mountains - in any season - including summer!

Fog and low clouds complicate life for those following an itinerary and, progressively, they even confuse those who know the area well.

The consequences are:

• finding yourself in an unknown area;
• loss of GPS signal (or much less accurate: 
  air density varies greatly, and reception gets much worse, like being in a forest);
• facing difficulty and unforeseen travel times 
  for the path you're on;
• additional expenditure of time and energy and the risk of having to camp 
  in inhospitable places;
• encountering obstacles and paths that are sometimes impassable, with sheer drops or cliffs. 

TIPS

Before the fog appears, try to establish your position using GPS, or using a map, with or without altimeter and compass.

Try to fix in your mind the direction you need to follow: it's often wiser to retrace your steps rather than plough through the fog, moving further away from your departure point!