From the school curriculum, everyone knows that water can be in three states of aggregation - solid, liquid and gaseous. Solid water is ice. But not everyone knows that ice can be different and even have the property of fluidity. It is about this type of ice, glacial, that will be discussed in this article.
So different
Today it is known about three varieties of amorphous ice and its 17 crystalline modifications. According to the degree of development, it happens at the initial stage (intravenous, needles), young (phial and nilas, gray and white), perennial or pak. By its location, it can be motionless or frozen to the shores (fast ice) and drifting.
By its age, ice is spring (formed before the summer), annual and perennial (there are more than 2 winters).
But by its origin, there are much more types of ice:
- Atmospheric: frost, snow and hail.
- Water: bottom, intra-water, integumentary.
- Underground: veined and cave.
- Glacier ice is a type of ice that forms glaciers on our planet.
Glacial
Glacier ice is one that is formed from snow above a snow line. This is a special ice that consists of transparent bluish large crystals, the axes of which eventually acquire a certain orientation.
Glacier ice is characterized by stripes. This is due to the processes of its formation. In addition, an important property of glacial ice is its fluidity: under the influence of gravity and its own pressure, glacier layers move along the surface. Moreover, the speed of this movement is different: in the mountains glaciers move 20-80 cm per day, and in the polar zones their speed ranges from 3 to 30 cm per day.
How is it formed
The process of glacier ice formation is rather complicated. In short, the snow that falls in the glaciers condenses over time and turns into firn - opaque and granular ice. The pressure of the upper layers of snow is squeezed out of the firn, and its grains are soldered. As a result, a transparent and blue mass of glaciers is formed from an opaque white firn - this is glacier ice (the photo at the beginning of the article is the Knick Glacier in Alaska).
The peculiarity of glacial ice is the lack of layering, constant fluidity and huge mass (1 cubic meter of snow, for example, weighs up to 85 kg, firn - up to 600 kg, and glacier ice - up to 960 kg).
Why is it flowing
Glacier ice is plastic, which explains its ability to flow. The pressure of the upper layers (the zone of accumulation or nutrition of the glacier) lowers its melting point, and melting begins at a temperature below zero degrees. Thus, the lower layers (ablation or discharge zone) begin to melt, and the resulting water is a “lubricant” for the advancement of the upper layers of ice.
If the movement is small, the water freezes again. But in another place the same process takes place, and in general the ice mass is constantly flowing. Moreover, ice flows from the places where it is thicker to the place where it is thinner - from the center to the outskirts.
At the same time, glacier ice breaks and cracks. When accumulation prevails over ablation, the glacier sets in. And vice versa. And that is precisely why throughout the winter streams and even rivers continue to flow from some glaciers.
Fresh and clean water
During the formation of glacial ice, all impurities are squeezed out of it, and the water that forms it is considered the cleanest. Glaciers on our planet occupy 166.3 million square kilometers of land (11%) and accumulate 2/3 of all fresh water on Earth, and this is about 30 million square kilometers.
Almost all of them are located in the polar region, but there are also in the mountains, and even at the equator. Greenland (10%) and Antarctic (90%) glaciers in some places descend to the waters of the oceans. Chunks breaking off from them form icebergs of glacier ice.
Global warming and glaciers
Recent studies by scientists have shown that the rate of ice melting over the past five years has increased 3 times. This means that in the coming decades, melting glaciers can lead to a rise in sea level by 3.5 meters by 2070. But this is not the only problem in this aspect.
In addition to changing ecosystems and reducing biodiversity, this promises us desalination of the world's oceans and a shortage of drinking water. But there are quite unexpected consequences of their melting.
Melting glaciers can change the climate on the planet. And there are many examples of this. So, once the Tien Shan (China) was called the "green labyrinth" - glacier water was enough for the development of agriculture. Today it is an arid region.
And even if hydropower wins in the short term, in the long run it will become completely useless. The tourism sector will also suffer, the ski resorts will be the first to feel it.
