• AVALANCHES •
Avalanches are huge storms of ice but some avalanches may even consist of other materials such as rock, mud or even soil, that run down a slope due to the forces of gravity. An avalanche lasts for a very brief time but still it causes a lot of destruction, sweeping out everything in their path.
Scientifically, an avalanche is defined as a large mass of falling or sliding material. Avalanches can be composed of rock, snow, soil, or ice. Volcanic eruptions can cause avalanches.
What causes an avalanche?
An avalanche is typically triggered when material on a slope breaks loose from its surroundings; this material then quickly collects and carries additional material down the slope. Main causes of an avalanche are activities such as earthquake tremors, human-made disturbances, or excessive rainfall on high gradient slopes, often where materials are loosely bound or weathered.
Avalanches of snow result when weak layers within a snow pack fail to support the weight of the snow above it and collapse, causing the overlying snow to break free and flow downhill.
Types of Avalanches
Avalanches are often classified by what they are made of, for example snow, ice, rock or soil avalanches. A mixture of these would be called a debris avalanche.
•Rock avalanches: Avalanches which consist of large segments of shattered rock.
•Snow avalanches: Avalanches, consisting of snow slides. Their speeds can reach over 200 m per hr (300 km per hr).
Here are the conditions when an avalanche can occur:
•Steepness- slopes under 25 degrees and over 60 degrees have a low avalanche risk because of the angle of repose for snow. Slopes with the most dangerous steepness are favorite for skiing.
•Direction- Solar heating and wind influence their direction.
•Surface- Surface avalanches are more common on slopes having grass.
Humans and Avalanches
Avalanches are also triggered by humans - because of the additional weight, kicks during skiing (e.g. during jumps) or intentionally by explosives, slope-cuts and other means. Opposing common thought, avalanches are rarely caused by loud sounds. More than 90% of avalanche victims worldwide are due to avalanches triggered by the victim or someone in the victim's party.
Avalanches have an enormous impact on the region.
In essence we can say-"The igloos would melt down there,
For the eskimos nobody would care.
A common thought, the children share-
"Oh! Avalanches are just so mere."