During an avalanche, a mass of snow, rock, ice, soil, and other material slides swiftly down a mountainside. Avalanches of rocks or soil are often called landslides. Snowslides, the most common kind of avalanche, can sweep downhill faster than the fastest skier.

They occur in two general forms, or some combination: slab avalanches made of tightly packed snow, triggered by a collapse of an underlying weak snow layer, and loose snow avalanches made of looser snow. After being set off, avalanches usually accelerate rapidly and grow in mass and volume as they capture more snow.

Avalanches can be triggered by wind, rain, warming temperatures, snow and earthquakes. They can also be triggered by skiers, snowmobiles, hikers, vibrations from machinery or construction.

4 Types of Avalanches

• Loose Snow Avalanche. They are common on steep slopes and are seen after a fresh snowfall.
• Slab Avalanche. Loose Snow Avalanches in turn could cause a Slab Avalanche, which are characterized by a the fall of a large block of ice down the slopes.
• Powder Snow Avalanche.
• Wet Snow Avalanche.

Slab avalanches

Avalanches are most common during the winter, December to April in the Northern Hemisphere, but they do occur year-round. To get an avalanche, you need a surface bed of snow, a weaker layer that can collapse, and an overlaying snow slab. The highest risk period is during and immediately after a snow storm.

The U.S. and Canada use a five-category estimation of the avalanche danger: Low, Moderate, Considerable, High and Extreme.

A 45-degree pitch is equivalent to a 100-percent grade, and both mean that a run descends one vertical foot for each horizontal foot. “In perspective, a very steep highway-pass road is approximately 7 percent or about 4 degrees,” according to the Highlands Extreme Guide trail map.

35 to 50 degrees

the maximum gradient beyond which it is practically impossible to groom is 90 degrees. After that, the laws of gravity dictate that the grooming machine will not put pressure on the slope, but will fall away from it. Anyway, snowHeads is much more fun if you do.

Avalanche Problem is a term used by avalanche centers in the US and Canada to describe the avalanche hazard by breaking it down into 4 elements:

• Problem type (sometimes called “avalanche character”).
• Location.
• Likelihood.
• Size, or destructive potential.

Field Service Advisor, Eric Hovan, demonstrates how steep a 30 degree slope is by first walking up and down and then driving the same course with a Ventrac 4500 Tractor. 30 degrees is equivalent to a 58% grade which is another way to describe the magnitude of a slope.

8 of the steepest and scariest ski runs in the world

• Mayrhofen, Austria. Summit altitude: 2,000m.
• Jackson Hole, Wyoming, USA. Summit altitude: 3,185m.
• Courchevel, France. Summit altitude: 3,185m.
• Kitzbühel, Austria. Summit altitude: 1,665m.
• Avoriaz, France.
• Delirium Dive.
• Val-d’Isère, France.
• Les Deux Alpes, France.

Slopes vs. gradients vs. % grades

57.7%

100 foot divided by 12 inches increase by 2% = 12.24 inches ,which is just a bit short of 1/4″ increase every foot of the 100 feet. So if you had a 12 inch rule completely ‘level’ , Than measure 0.24 of inch on one side and readjust the ruler to so one side is 0.24 inches higher than you will have created a 2 % slope.

2%

1% as a decimal is 0.01 and hence the slope is 0.01. That means for a run of pipe of a certain length the rise must be 0.01 times the length. Thus for you example, since the length of the run is 80 feet which is 80 × 12 = 960 inches the rise must be 0.01 × 960 = 9.6 inches.

Slope as a Percentage Convert the rise and run to the same units and then divide the rise by the run. Multiply this number by 100 and you have the percentage slope. For instance, 3″ rise divided by 36″ run = .

Numerically speaking, slope is the change in elevation (rise) over a given distance (run). In other words, the number of feet the land rises or falls over a horizontal distance. Slope is often described in terms of percent. A 2:1 slope is also 50% slope, and a 1:1 slope is 100% slope.

In the United States, maximum grade for Federally funded highways is specified in a design table based on terrain and design speeds, with up to 6% generally allowed in mountainous areas and hilly urban areas with exceptions for up to 7% grades on mountainous roads with speed limits below 60 mph (95 km/h).

If you “rise up”, the number is positive; if you “rise down”, the number is negative. Now, you ALWAYS “run over”! If you follow the procedure correctly, you will always run over to the right.

If the slope is positive, then the rise and the run need to either be BOTH positive or BOTH negative. If the slope is negative, then the rise and the run have to be opposites of each other, one has to be positive and one has to be negative. In other words, you will be going up and to the left OR down and to the right.

Since slope equals rise over run, the slope of the line is y2 − y1 over x2 − x1. We’ve now got a new way to write the slope formula and to calculate the value of a slope. Slope is the difference between the y-coordinates divided by the difference between the x-coordinates.

Subtract the first X-axis point from the second one to calculate the run. In the example, 5 minus 2 gives you a run of 3. Subtract the first Y-axis point from the second one to calculate the rise. Continuing with the example, subtract 4 from 9 to get a rise of 5.

First, identify two points on the line. Then, you could use these points to figure out the slope. In this tutorial, you’ll see how to use two points on the line to find the change in ‘y’ and the change in ‘x’.