Tuesday, July 5, 2011

Terrain Training Tuesday: The Desert Part 4

Surviving and evading the enemy in an arid area depends on what you know and how prepared you are for the environmental conditions you will face. In a desert area there are seven environmental factors that all minions must consider:
  • Low rainfall.
  • Intense sunlight and heat.
  • Wide temperature range.
  • Sparse vegetation.
  • High mineral content near ground surface.
  • Sandstorms.
  • Mirages.

Low Rainfall

Low rainfall is the most obvious environmental factor in an arid area. Some desert areas receive less than 10 cms of rain annually, and it comes in brief torrents that quickly run off the ground surface. You cannot survive long without water in high desert temperatures but lucky for us we covered this last week and are completely in control of the whole water thing.

Intense Sunlight and Heat

Intense sunlight and heat are present in all arid areas. Air temperature can rise as high as 60 degrees C during the day. Heat gain results from direct sunlight, hot blowing winds, reflective heat and conductive heat from direct contact with the desert sand and rock.  The temperature of desert sand and rock averages 16 to 22 degrees C more than that of the air and will increase the body's need for water. To conserve your body fluids and energy, you will need a shelter to reduce your exposure to the heat of the day. Travel at night (preferably with moonlight to help you see) to lessen your use of water.  Radios and sensitive equipment exposed to direct intense sunlight may also malfunction.

Wide Temperature Range

Temperatures in arid areas may get as high as 55 degrees C during the day and as low as 10 degrees C during the night. The drop in temperature at night occurs rapidly and will chill a person who lacks warm clothing and is unable to move about. The cool evenings and nights are the best times to work or travel.

Sparse Vegetation

Vegetation is sparse in arid areas. You will therefore have trouble finding shelter and camouflaging your movements. During daylight hours large areas of terrain are visible and easily controlled by small opposing forces.  If travelling in hostile territory, follow the principles of desert camouflage:
  • Hide or seek shelter in thicker growths of vegetation and cover from oblique observation.
  • Use the shadows cast from brush, rocks, or outcropping. The temperature in shaded areas will be 11 to 17 degrees C cooler than the air temperature.
  • Cover objects that will reflect the light from the sun.
Before moving, survey the area for sites that provide cover and concealment. You will have trouble estimating distance. The emptiness of desert terrain causes most people to underestimate distance by a factor of three: What appears to be 1 km away is really 3 km away.

High Mineral Content

A lot of arid regions have areas where the surface soil has a high mineral content (borax, salt, alkali, and lime). Materials in contact with this soil wear out quickly, and water in these areas is extremely hard and undrinkable. Wetting your outfit in such water to cool off may cause a skin rash and no one wants that.


Sandstorms occur frequently in most deserts. The "Seistan" desert wind in Iran and Afghanistan blows constantly for up to 120 days!  Expect major sandstorms and dust storms at least once a week.
The greatest danger is getting lost in a swirling wall of sand. Wear goggles and cover your mouth and nose with cloth. If natural shelter is unavailable, mark your direction of travel, lie down, and sit out the storm.  Dust and wind-blown sand interfere with radio transmissions. Therefore, be ready to use other means for signalling such as mirrors.


Mirages are a fascinating optical phenomena caused by the refraction of light through heated air rising from a sandy or stony surface. They occur in the interior of the desert about 10 km from the coast. They make objects that are 1.5 km or more away appear to move, making it difficult for you to identify an object from a distance. It also blurs distant range contours so much that you feel surrounded by a sheet of water from which elevations stand out as "islands."

To cope with this if you can get to high ground (3 meters or more above the desert floor), if you can get above the superheated air close to the ground you can overcome the mirage effect. Mirages make land navigation difficult because they obscure natural features. You can survey the area at dawn, dusk, or by moonlight when there is little likelihood of mirage.

Now that's a mirage...the perfect desert outfit I'd say....

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