Avalanche rescue dogs
Avalanches are caused by a break of an unstable balance of a mass of snow caused by the weight of the same; the snow becomes so heavy it is no longer able to hold its own weight causing it to collapse. Other things that can cause avalanches are wind, abrupt temperature changes, as well as other factors that create internal tension on the coat of the snow. There are several types of avalanches be it in function of the snow (powder snow, or wet snow etc) or because of the amount of weight and coats in the snow (on the surface or inside). Some avalanches are caused by a consequence of a rupture of snow from a layer of unstable icy snow. These avalanches are very dangerous because of the speed they can pick up and the amount of snow they drag along with them.
Most occur on slopes of 30 - 50, although there is a risk of an avalanche starting at 20. When the slope is above 50 it presents less danger, because the smaller and more frequent snow avalanches without cohesion that occur while it is snowing, goes letting off the snow little by little. However, slopes that near the critical limit of 30 can go accumulating large quantities of snow that can cause a huge and catastrophic avalanche. Snow dust avalanches incline forward as if they were pointing and they go increasing in volume as they advance. These can happen in slopes of 40 to 60 and their velocity increases little by little as it travels. These are formed by snow with little cohesion.
Some avalanches are caused because of humid snow. This type of snow is a lot denser that snow dust, meaning that when this type of avalanches occurs, it looks like a streak of lava flowing down slowly. Surface avalanches usually break off of the exterior layers and they then frequently leave a hard and cold layer. Full depth avalanches in this case breaks off of the entire layer of snow and emerges over an entire terrain. These avalanches are more common on slopes with smooth ground and on rock slabs.
In general the most dangerous slopes and hills as far as avalanches is concerned, are those that are at a 25 to 45 angle approximately, although logically, the nature of the terrain the snow is on can favor or annul the risks of an avalanche. A slope at an 18 angle with lots of long grass or that has a uniform terrain is at more risk of an avalanche occurring than a slope at a 45 with trees and rocks that would anchor the masses of snow. Between the lightest snow that falls on a windless day with low temperature (snow dust), weighing about 30 to 50 kilograms per m3, there are varied and gradual types of changes, although to make it easier, both basic types being snow dust and wet snow or heavy snow could be grouped up as those that could cause the most amount of damage.
Both these types could cause serious damage to a person that is buried underneath them due to compression, and when they crash against rocks, trees etc they are very potent. Snow dust can cause a person to die due to asphyxiation motivated by inhaling the fine dust through the respiratory tubes; on the other hand wet and heavy snow can cause asphyxiation by compressing a person's body so tightly that the person is not able to move at all or breath. Another risk or lesion that could occur when someone is buried by an avalanche is what is known as the crush-injury.