Category Environment

WHY DO GLACIERS LOOK BLUE?

Glacial ice is a different color from regular ice. It is so blue because the dense ice of the glacier absorbs every other color of the spectrum except blue — so blue is what we see!

It’s Not Just Frozen Water!

Sometimes the glacial ice appears almost turquoise. Its crystalline structure strongly scatters blue light. The ice on a glacier has been there for a really long time and has been compacted down so that its structure is pretty different from the ice you normally see. Glacial ice is a lot different from the frozen water you get out of the freezer.

It’s Not Just Frozen Snow!

Glacial ice is not just frozen compacted snow. There are other things in the ice that make it much different from the ice in your home. Glaciers move through rock and soil as they carve their way down a slope. This means the ice is going to have a lot more ingredients than just water.

Credit: Alaska Satellite Facility

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WHAT ARE THE CRACKS IN GLACIERS CALLED?

Crevasse, fissure or crack in a glacier resulting from stress produced by movement. Crevasses range up to 20 m (65 feet) wide, 45 m (148 feet) deep, and several hundred metres long. Most are named according to their positions with respect to the long axis of the glacier. Thus, there are longitudinal crevasses, which develop in areas of compressive stress; transverse crevasses, which develop in areas of tensile stress and are generally curved downstream; marginal crevasses, which develop when the central area of the glacier moves considerably faster than the outer edges; and bergschrund crevasses, which form between the cirque and glacier head. At the terminus of the glacier many crevasses may intersect each other, forming jagged pinnacles of ice called seracs. Crevasses may be bridged by snow and become hidden, and they may close up when the glacier moves over an area with less gradient.

Credit: Britannica

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HOW DO GLACIERS FORM?

In places high above the snow line, where more snow gathers than melts, it gets tightly packed. New snow falls and buries the old snow, which turns more dense and grainy. This is called firn and the process is called firnification. Layers of firn build up on top of each other and as they get thick and heavy, the grains of firn merge into huge mases of ice. Over time, the tightly compacted ice becomes so heavy and exerts so much pressure that the glacier slowly starts to move and slide downhill.

Glaciers are huge masses of ice that cover the basement rock. They are found only in regions where snow cover is permanent, that is, at the poles and at high altitude.

At low temperatures, snow does not melt. It accumulates and is compacted into ice. This gradual metamorphosis, which can take several decades, results in the formation of an enormous mass of ice, several dozen meters thick–a glacier.

Propelled by its own weight, a mountain glacier may become detached from the rock wall and slide downward. It slowly flows into the valley like a river of ice. As it descends, the glacier picks up rocks and debris, which accumulate in the form of mounds, called moraines.

If the climate warms, the glacier melts. We say that it recedes. It leaves behind a profoundly eroded landscape composed of wide, flat bottom valleys and many lakes.

Credit: Britannica

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WHICH IS THE LARGEST GLACIER?

The world’s largest glacier is the Lambert glacier in Antarctica, according to the United States Geological Survey. The glacier is more than 60 miles (96 km) wide at its widest point, about 270 miles (435) long, and has been measured to be 8,200 feet (2,500 meters) deep at its center.

Glaciers form when the annual snowfall in a region exceeds the rate at which the snow melts, allowing enormous amounts of snow to accumulate over time. The fallen snow compresses into solid ice under its own weight, forming solid sheets of ice.

And these sheets are in motion. Glaciers flow like very slow-moving rivers, and can stretch over hundreds of miles. The Lambert glacier flows at a rate of about 1,300 to 2,600 feet (400 to 800 meters) each year.

Credit: LIVE SCIENCE

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WHAT ARE GLACIERS?

The word glacier comes from the French word glace, meaning ice. A glacier is a huge, slow-moving mass of ice. Glaciers are generally seen in mountainous regions where temperatures always remain close to freezing and a massive amount of ice accumulates. Forced by the weight of the ice and the pull of gravity, these sheets of ice start moving, almost like a river, although most glaciers move no more than one  centimetre a day.

Glaciers are massive bodies of slowly moving ice. Glaciers form on land, and they are made up of fallen snow that gets compressed into ice over many centuries. They move slowly downward from the pull of gravity.

Most of the world’s glaciers exist in the polar regions, in areas like Greenland, the Canadian Arctic, and Antarctica. Glaciers also can be found closer to the Equator in some mountain regions. The Andes Mountain range in South America contains some of the world’s largest tropical glaciers. About 2 percent of all the water on Earth is frozen in glaciers.

Glaciers can range in age from a couple hundred to thousands of years old. Most glaciers today are remnants of the massive ice sheets that covered Earth during the Ice Age. The Ice Age ended more than 10,000 years ago. During Earth’s history, there have been colder periods—when glaciers formed—and warmer periods—when glaciers melted.

Scientists who study glaciers are called glaciologists. Glaciologists began studying glaciers during the 19th century in order to look for clues about past ice ages. Today, glaciologists study glaciers for clues about global warming. Old photographs and paintings show that glaciers have melted away from mountain regions over time. Indeed, glaciers worldwide have been shrinking—and even disappearing—at an accelerated rate for the past several decades.

Credit: National Geographic Society

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WHAT IS THE DEEPEST POINT ON EARTH’S SURFACE?

It’s beneath the surface of the Pacific Ocean to the southeast of Japan. There, you’ll find a deep, crescent-shaped trench. This is called the “Mariana Trench.” Near the southern tip of the crescent, there is a small slot-shaped area. This is the deepest point on Earth—Challenger Deep.

The bottom of Challenger Deep is about 36,000 feet below sea level. That’s nearly seven miles! This makes it the deepest known place on Earth.

The Challenger Deep is named after a British Royal Navy ship called the HMS Challenger. It was the first ship to measure the depths of what is now known as the Challenger Deep. The Marianas Trench in the western Pacific is 11,030 m deep.  

The trench was measured by “sounding.” This involves dropping a very long line with a weight at the end into a body of water. Today, scientists and researchers use sonar to study ocean depths.

Only four descents into the Challenger Deep have ever been achieved. The first was in 1960 by a vessel called the Trieste. The Trieste was a special kind of ship called a “bathyscaphe,” invented by Jacques and Auguste Piccard. The name “bathyscaphe” is taken from the Greek words for “deep” and “ship.”

Credit: WONDEROPOLIS

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