US Army mountaineering techniques (basic)

The success or failure of a mission is often determined by the weather. When
planning airmobile and airborne operations, military plans must be flexible. You
must anticipate the weather as part of your planning in order to turn an important
weather factor in your favor. The clouds that often cover the tops of mountains
and the fogs that cover valleys are an excellent means of concealing movements
that are normally made during darkness or in smoke. Limited visibility can be
used as a combat multiplier.
The safety or danger of almost all high mountain regions depends on the weather,
especially in winter. A change of a few degrees in temperature above or below the
freezing point may affect the ease and speed of travel. Terrain that can be crossed
swiftly and safely one day may become impassable or highly dangerous the next
due to snowfall, rainfall, or a rise in temperature. The reverse can happen just as
quickly. The prevalence of avalanches depends on terrain, snow conditions, and
weather factors.
Some mountains, such as those found in desert regions, are dry and barren with
temperatures ranging from extreme heat in the summer to extreme cold in the
winter. In tropical regions, mountains are often covered by lush jungles with
heavy seasonal rains and little temperature variations. High rocky crags with
glaciated peaks can be found in mountain ranges at most latitudes along the
western portion of the Americas and Asia.
Severe weather may decrease morale and increase basic survival problems. These
problems can be minimized when you have been trained to accept the weather by
being self-sufficient. As a mountain soldier, properly equipped and trained, you
can use the weather to your advantage in combat operations.
3. Mountain Air.
Mountain air is relatively pure. The higher the elevation, the more pure it becomes.
Above 4,500 meters, air is almost germ-free. The composition of the air of high altitudes
is different than air at sea level. Falling snow also purifies the air by capturing and
holding many of the impurities in the air.
Pressure is low in mountainous areas due to the altitude. The barometer usually
drops 2.5 centimeters (1 inch) for every 300 meters gained in elevation. This
equates to a 3 percent drop in pressure for an increase of 300 meters in elevation.