Avalanches are just one of many natural disasters that kill people every year. The difference to Alaskans is that this disaster hits a little closer to home than most. The fear of hurricane and tornado are not existent in my region, and even earthquakes are seen more as a little shake then any threat. Physics plays a huge part in avalanches, thermodynamics, statics, and gravity are just a few elements of these disasters. The map above confirms that Alaska is at high risk for avalanche. As a result of this threat, learning about avalanches is a necessity when recreating or working in high avalanche areas.
In order to better understand Avalanches, it makes sense to first learn about what avalanches are compose of, snow. Snow forms when atmospheric conditions cause water vapor to condense. However, it is obvious that all snow doesn't have the same structure.
The density of fresh snowfall is dependent on both the kind of snow crystal and the air temperature. In cold, calm conditions the snowfall is the lightest. While in warmer climates, where graupel and needle crystals fall, the snowfall is the densest.
When looking at a cross section of snowfall it is often evident what weather conditions formed the cross section. This is due to the different densities and structures of the snow layers. The bonds between snow layers are large factor in avalanches. If there is a weak bond between layers, the top layer can easily slide off the bottom layer. When this happens it is called a slab avalanche. Other layering characteristic will create other avalanches and hazards, such as ice avalanches and cornices.
Whenever traveling in avalanche country it is important to be aware of your environment. Steep gullies and wide plains are perfect paths for avalanches. Ridges and unconformities in the terrain may help to slow down an avalanches speed. The severity of an avalanche is directly related to the terrain in which it happens.
One of the most important factors to consider is the slope of the mountain or hill. Most avalanches occur between 20 and 50 degrees like the diagram above shows. However, the largest avalanches occur between 30 and 45 degrees, and the areas which have the greatest frequency of avalanches are between 35 and 40 degrees.
Lake-Effect snow has a range of different intensities depending upon certain factors. The difference between the air temperature and the water temperature will determine how much moisture is taken into the air. Warmer water and colder air makes for more snow. Also the distance the air has to travel across the lake will determine how much moisture the air is able to obtain. The ability of the storm to travel inland will be determined by the intensity of the storm’s winds. Storms also are able travel farther inland in late fall and early winter.
The heavy annual snowfall on Lassen Peak creates fourteen permanent patches of snow on and around the mountain top, despite Lassen's rather modest elevation, but no glaciers.
Typically impacting a small area, one location could see in excess of a foot of snow where a few miles away, could be only seeing flurries. LES (Lake Effect Snow) can come quickly and produce conditions that are very hazardous for traveling. Things like this as well as other impacts are important to note and as forecasters, try to inform the public to be prepared for an event like this. To understand the whole idea of lake effect snow, one must travel to the past where this phenomenon was first discovered and from there; move forward in time to see the progress that has been made not only in understanding this, but also forecasting it as well.
- The snow compresses to become ice and flows through the glacier into the ablation zone where it is lost.
Great forces from the earth helped form the great basin and has forced these mountains to grow and climb. There were at least four periods of glacial advance that covered the mountain range in a thick coat of ice. Many glaciers formed during this period but today there’s only a few small glaciers that have remained in the park and they are known as the southernmost glaciers in North America. The glaciers carve the deep valleys and craggy peaks that are seen in the Sierra Nevada Mountain
On January 12, 1888, the Children’s Blizzard hits part of the Northwest Plains. This blizzard is also known as the Schoolchildren’s Blizzard or Schoolhouse Blizzard (Potter). The name is associated with schoolchildren’s because it was mostly children trying to go back home, that froze to death along their way. It was such a beautiful day, just like one of those days someone would have in April, that no one would have suspected such a bitter snowstorm to come. The blizzard came when a cold, arctic wind from Canada met with the winds that came from the south. Everyone, including the kids, were dressed up with short sleeves. Just like how somebody would wear on a hot, spring day. The air from Canada carried heavy snow and harsh winds along with it, causing the hurricane (Blizzard Brings Tragedy to Northwest Plains). The Children’s Blizzard hit both of South and North Dakota (back then in 1888, it was one territory), Nebraska, Minnesota, Montana, Wyoming, and Idaho, causing lots of heartbroken and unexpected deaths (McLeod).
This glacial trough was formed by the 3rd out of 4 glaciers in the Aspen area. This glacier could have been anywhere 4 million to 18,000 years ago. Glacial troughs are u-shaped valleys that are carved out when glaciers flow down them. The glacier that ran down this valley’s cirque helped from pyramid peak.
Snow is a concept that only a few people really know about. It seems like most people hate snow with a burning passion. However, the true northerners praise every day that it snows; mostly because it does not happen a lot. At one point everyone that participates in a snow sport has to hope that it will snow every winter. Unfortunately, our hopes and dreams do not always come true. That was why snowmaking was developed in the 1980s and has been upgraded every year so maximum snow production is possible. The first reason was to fill in the gaps that Mother Nature left out. However, now the amount of snow we receive is drastically less than what it used to be. Instead of making snow to fill in the gaps, we have to make most of the snow we ski
According to Richard Wild, the first use of the word ‘blizzard’, to define a set of weather conditions, was used in 1860 to describe a mid-west weather event in which “warm and balmy” condition suddenly took a turn for the cold. The result: freezing temperatures, heavy snowfall and massive drifts of snow (1996, web). A blizzard is the most severe of all types of snowfall. Its effects exceed those of heavy snow warnings, flurries, blowing and drifting snow and traveler’s warnings. Blizzards are caused through a confluence of cold-air, moisture and lift (which is necessary to raise the cold air and form it into clouds which produce precipitation) (Weather Almanac, 2004, p. 81). In the case of a blizzard warning, inhabitants can expect winds of over 35 mph, heavy accumulation of light, powdery snow and low visibility. These conditions make it difficult for individuals to get to and from work and school, which, in turn, makes it difficult for businesses to function, governments to deliver services and utility companies to deliver essential services (e.g. electricity, gas, etc.).
Although Iran is located in the arid and semi- arid climate, but this glaciated area is sustained by moisture- laden southerly wind originate from the Caspian Sea. These winds collide with the Northern slopes of the Tackt e Solaiman mountainous and produce an estimated average snowfall of about 452 cm/year. This orographic precipitation occurs during the 65 days in year. Also, a significant amount of precipitation falls during the October- December (Vaziri, 2003). The surface of Alamkouh is characterized by a system of ridges and depressions and oriented parallel to the overall flow direction. The most part of the Alamkouh surface is covered by debris. Typical origins of such debris accumulation include debris-laden snow avalanches, episodic rock avalanches and long-lasting rockfall activity, heavy rains or weathering processes.
Before examining the Northridge event, understanding the naturally occurring hazard that is an earthquake will help to better understand exactly what happened and why it was such an important geological event. With four distinct layers, two layers, the crust and upper portion of the mantle, compose the skin that is the surface layer of the Earth. The crust is not a single, continuous piece. It is actually several different pieces, or plates, that come together to form the puzzle that comprises the surface of the Earth. These plates are in constant motion rubbing against one another. These areas, known as fault lines, where the plates rub up against one another have spots where one plate ”gets stuck while the rest of the plate keeps moving. When the plate has moved far enough, the edges unstick and is how most of the earthquakes around the world occur” (Wald, 2012). The energy stored from the friction of the two plate...
To begin with, the landing of the snow on the road caused many damages to them. This was because the levels on which the roads were raised were in different proportions. This, therefore, prevented lack of flow to be experienced on the roads. Moreover, the cracks that were observed on the roads came about because of the difference in the temperatures of the country.
Wind tunnel and flight tests have shown that frost, snow, and ice accumulations (on the leading edge or upper surface of the wing) no thicker or rougher than a piece of coarse sandpaper can reduce lift by 30 percent and increase drag up to 40 percent. Larger accretions can reduce lift even more and can increase drag by 80 percent or more. (AOPA, 2002, 2).
Mudslides usually occur in hilly areas, for an example, when there was a mudslide in Bangladesh few months back, it occurred at Chittagong. Mudslides occur when a portion of a hill side becomes too weak to hold up its own weight. This is generally caused by an intense amount of rain fall. With all of the new water introduced into the slope the content of liquid makes it so heavy that gravity pulls it downward. Although water plays a major factor in creating the mud that flows in a mudslide the real reason that the land begins to slide is gravity. What happens is mudslides redistribute soil and sediments in a process that can be in abrupt collapses or in slow gradual slides.
U.S. Geological Survey. Worldwide Overview of Large Landslides of the 20th and 21st Centuries. 6 December 2010. 3 February 2011 .