Category: Geography Notes PPT

Agriculture is the practice of cultivating plants and livestock in order to provide facilities the human beings. In the rise of the sedentary human lifestyle agriculture was the key development. The cultivation of plant and food grains began years ago in order to provide food to the city population. Agriculture is the main need for the people to live in the society. Agriculture is the main source of livelihood, it provides a source for the people to earn. Most of the population in the rural areas is dependent on agriculture as their main source of income.

Agriculture contributes significantly to a country’s GDP that is the Gross Domestic Production of a country. By the passing of time, there are a number of revolutions that take place in order to improve agriculture throughout the world or a country. If we talk about agriculture, India has witnessed a number of revolutions, that is, the green revolution, yellow revolution, blue revolution, agriculture. Agriculture affects the biodiversity of a country depending upon agricultural activities.

The major agricultural products can be widely grouped into categories of food grains, fibers and raw materials.

Foodgrains included the grains or cereals that have been used for eating. Fiber crops are completely Commercial, they can not be eaten and are completely grown for making money. Raw materials are that category of crops that are completely grown for use as raw materials in industries in order to prepare other items. 

This article provided to help you to learn the topic of agriculture about the history of farming, Commercial farming, primitive farming, its characteristics, types of Commercial Farming, intensive subsidence character, and so on. This will help you to get a clear view of agriculture. Let’s have a look at it.

History of Agriculture 

The development of agriculture enables human civilization to grow rapidly. This agriculture that was started by hunting and gathering has now reached the stage of cultivation and industrial form of agriculture also.

The earliest food crop grown was rice which was followed by Moong, soya, azuki beans, etc. Sheep were domesticated in Mesopotamia first, cattle were domesticated in the areas of modern turkey, pig production emerged in Europe, East Asia, and South Asia. There are many hypotheses that are explained by the scholars for agriculture.

Irrigations, crop cultivation, and fertilizers were the advanced form of agriculture that was developed in the 17th century. Modern agriculture has raised or encountered issues such as water pollution, biofeedback, genetically modified organisms, farm subsidies leading to alternative approaches such as that of organic movements.

In the rise of sedentary human civilization agriculture is the key development. Farming of domestic species provided food surpluses that prompted people to live in cities. The history began some thousands of years ago. Pigs, sheep, and cattle were domesticated over 10000 years ago. Plants were cultivated independently in 11 regions of the world. Industrial agriculture based on a large scale in the 20th century came and dominated agriculture output. An estimated number of around 2 billion people still depend on subsistence agriculture.

The major agricultural products are broadly grouped into foods, fibres, fuels, and raw materials. Over one-third of the world’s workers are employed in agriculture and after that to the service sector.

 

Commercial Farming

Commercial farming is when farmers grow crops or rear animals for economic activity. Commercial farming needs to be practised on a large scale with more efficiency. The goal of the farmer is to earn profits from farming, hence the production and area of production need to be on a larger scale. This practice is also known as agribusiness and is intensively taken up and practised. It has also opened its doors for a lucrative business venture.

Due to the large production in commercial farming and despite its major benefits, it is a bit worrisome as it includes lots of fertilisers, pesticides, weed killers, and other sorts of chemicals.

Crops in this type of agriculture are completely grown in order to provide the farmers with the benefit of money. These crops are not for you to consume but only for the sale.

Here are Some of the Characteristics of Commercial Agriculture:

• Large scale production

• It is capital intensive

• It uses high yielding varieties

• It is produced mainly for sale purpose

• Heavy machinery and human labour is used

• Traditionally practised all year round.

Types of Commercial Farming include the Following:

Primitive Farming

Primitive farming or also known as simple subsistence farming (farming for the farm-family only) is the oldest form of agriculture and is still prevalent in some areas of the world. Primitive farming enabled people to take a step further on the economic ladder by learning the art of domesticating plants. In this type of farming, farmers grow crops for themselves and their families. The growing of crops is only limited. 

Its Characteristics Include the Following:

• Sites of farming are selected by experienced elders.

• Hill slopes are preferred because of proper drainage

• Forests are cleared by fire, as ashes add to the fertility of the soil

• This is also called slash and burn agriculture.

• The cultivated patches are usually very small

• Primitive tools are used in cultivation such as stick and hoe

Intensive Subsistence Agriculture

Intensive subsistence agriculture term is used to describe the type of agriculture which is characterised by high output per unit of land and low output per worker.

Although its nature has changed and is no longer subsistence. These are more sophisticated than primitive agriculture and are also known as monsoon type of agriculture

Its Characteristics Include the Following:

• Very smallholdings

• Farming is very intensive

• It requires much hand labour

• It uses animal and plant manures

• The dominance of padi and other food crops

Following are the Types of Subsistence Farming:

Shifting Cultivation: In this method, farmers clear the cultivated land and burn it afterwards. The ashes produced thereafter increase soil fertility. This method is known by different names in different regions. It is further practiced in South America and Southeast Asia. This method is not fit as by exhausting the quality of the soil of one place and then moving to another place for doing the same is not a solution.

Nomadic Herding: It involves herders and farmers traveling from place to place with their group of animals. The herders also provide wool, meat, hide, and dairy products from the livestock. This type of farming is very common in places like Rajasthan, Jammu, and Kashmir. Animals herd here are sheep, goats, camel, and yak

It is quite the opposite of primitive farming. Farmers practice this on wider areas of land, they use modern machinery and add chemical fertilizers for the betterment of crop production.

Whereas in primitive agriculture, all the age-old agricultural practices are done by using the age-old method by which agriculture was done in the past. In the primitive type of agriculture also there is a waste of energy and sources up to some extent without getting a good quality of the crops we were looking for.

Have you seen or heard of a mass movement land? Have you noticed the news that some roads in the mountains were closed due to landslides? Well, in this article, we will only discuss this mass movement of landmass. We will learn about the meaning of landslides, the impact of landslides, the causes of landslides, efforts to prevent or overcome them and so on. This article will help you understand a very important geographical phenomenon, namely landslides and related concepts.

Landslides are a natural phenomenon, but it involves many human activities which lead to the mass movement of landmass. In recent times we find the causes of landslides increasing day by day and the primary cause is deforestation. To survive, one needs to keep a check on these human activities.

More on the Topic

The movement of the rocks or debris etc., on a slope downwards, is called a landslide. It is a type of “mass wasting “, which refers to the movement of any mass, soil, or rocks under the influence of gravity. It is one of the natural hazards and can be a disaster if the damages occur in large amounts.

According to the Oxford learners dictionary, “landslides is a mass of earth, rock, etc. that falls down the slope of a mountain or a cliff “.

Types of Landslides

They can occur because of various reasons. We can classify them into four categories which are mentioned below:

It means falling of some material or debris or rocks etc., from a slope or a cliff which leads to a collection of this debris at the base of the slope.

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These can occur because of some fractures between the rocks and the tilt of the rocks because of gravity without collapsing. Here, we see the forward rotational movement of the material.

It is a kind of landslide when a piece of the rock slides downwards and gets separated from it.

It happens on flat terrain and gentle slopes and can occur because of softer material.

Causes of Landslide

Landslides are caused by various factors, which are mentioned below:

• It can be caused because of heavy rain.

• Deforestation is also one of the main reasons for landslides because trees, plants, etc., keep the soil particles compact and due to deforestation, the mountain slopes lose their protective layers because of which the water of the rain flows with unimpeded speed on these slopes.

• It can be caused by earthquakes as well.

For example, in the Himalayas, the tremor occurred because earthquakes unstabilized the mountains, which led to landslides.

• Volcanic eruptions in specific regions can also cause landslides.

• Landslides often occur in mountain regions while making roads and construction; a large number of rocks has to be removed, which can cause landslides over there.

• In the regions of North East India, landslides occur because of shifting agriculture.

• Due to the increasing population, a large number of houses are being created, which leads to the creation of a large amount of debris which can cause landslides.

Effects of Landslide

Let us look at the effects of landslides in points:

Landslides can disturb the social and economic environment with the number of other damages which are mentioned below:

Short Term Impacts

• The natural beauty of the area is damaged.

• Loss of life and property

• Roadblocks

• Destruction of railway lines

• Channel blocking because of the falling of rocks.

• It leads to the diversion of river water, which can cause floods as well.

Long Term Impacts

• Landscape changes can be permanent.

• The loss of fertile land or cultivation land.

• Erosion and soil loss can lead to environmental problems.

• Population shifting and migration.

• Effects on the sources of water.

• Some roads can be damaged or closed permanently.

Prevention and Mitigation

The following measures can be taken in this regard:

• The country should identify the vulnerable areas and actions should be taken in this regard on a priority basis.

• Early warning systems and monitoring systems should be there.

• Hazard mapping can be done to identify the areas which are more prone to landslides.

• Restriction on the construction in the risky areas should be imposed.

• Afforestation programs should take place.

• Restricting development in landslide areas and protecting the existing ones.

• The country should specify codes or standards etc. For the construction of the buildings and other purposes in such areas of risk.

• Insurance facilities should be taken by the people to deal with the loss.

• Terrace farming should be adopted in hilly areas.

• Response teams should be quick to deal with landslides if they occur.

Landslides in India

It is one of the natural hazards in India, which affects 15% of the geographical area of our country. Due to several factors, India is divided into the following vulnerability zones, which are shown in the table below:

Did You Know?

The North India Flood Mudslides that occurred in Kedarnath, India in June 2013 was one of the deadliest landslides in the world. Around 5700 people died in this disaster. It was one of the worst disasters ever to occur in India.

Endnote:

Thus, in this article, we have covered a very important topic namely landslides. We have covered its related concepts like causes, effects, prevention, and mitigation, etc. Hence, it is very important to learn these kinds of topics. These notes will help you in Geography, Environment, and Disaster Management. So, we have read about the landslide information, effects of landslides, etc. Let’s look at some FAQs in the following.

Magnesite is a magnesium carbonate mineral with MgCO3 as its chemical composition. It gets its name from the fact that it contains magnesium. Magnesite is formed when magnesium-rich rocks or carbonate rocks are altered by metamorphism or chemical weathering.

Magnesite is used to make magnesium oxide (MgO), which is used in the steel industry as a refractory material and as a raw material in the chemical industry. Magnesite is also used as a gem and lapidary stone in small quantities.

Magnesite Ore

In mMagnesite ore, the mMagnesite is found as veins in ultramafic rocks, serpentinite, and other magnesium-rich rock forms, as well as as an alteration element, in both contact and regional metamorphic terrains. These magnesites are mostly cryptocrystalline and contain opal or chert as silica. Magnesite is also found as a secondary carbonate in the regolith above ultramafic rocks, as well as in soil and subsoil, where it is formed as a result of magnesium-bearing minerals being dissolved by carbon dioxide in groundwaters.

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Magnesite Formations

• The talc carbonate metasomatism of peridotite and other ultramafic rocks may result in the formation of magnesite. Magnesite is formed when olivine is carbonated in the presence of water and carbon dioxide at high temperatures and pressures, as in the greenschist facies.

• Magnesite has been discovered in sedimentary rocks, caves, and soils. Its low-temperature formation is known to necessitate alternating periods of precipitation and dissolution.

• Magnesite has been discovered in the meteorite ALH84001 as well as on Mars itself. Magnesite was discovered on Mars by using infrared spectroscopy from space. Mg-carbonates have been found near Jezero Crater and are thought to have formed in the lacustrine climate. The temperature at which these carbonates form is still a point of discussion. The magnesite from the Mars-derived ALH84001 meteorite has been attributed to low-temperature formation. The formation of magnesite at low temperatures may be essential for large-scale carbon sequestration.

• Magnesite can also be found in skarn deposits and dolomitic limestones, where it is associated with wollastonite, periclase, and talc as a result of metasomatism.

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Magnesite Uses

• Magnesite can be burned in the presence of charcoal to produce MgO, which is known as periclase in the form of a mineral, similar to how lime is made. Magnesite is burned in large amounts to produce magnesium oxide, a refractory material used as a lining in blast furnaces, kilns, and incinerators. Calcination temperatures determine the reactivity of resulting oxide products, and the terms “light burnt” and “dead burnt” refer to the product’s surface area and resulting reactivity, which is usually measured by an industry metric called the iodine amount. The term “light burnt” refers to calcination that starts at 450°C and goes up to 900°C, resulting in a substance with a lot of surface area and reactivity. Over 900°C, the material loses its reactive crystalline structure and transforms into the chemically inert ‘dead-burnt’ substance, which is ideal for use in refractory materials including furnace linings.

• Magnesite is also used as a binding agent in flooring. It is also used as a catalyst and filler in the manufacture of synthetic rubber, as well as the manufacture of magnesium chemicals and fertilisers.

• Magnesite beads can be cut, drilled, and polished to make them suitable for jewellery making. Magnesite beads can be coloured in a wide range of vibrant colours, including a light blue hue that resembles turquoise.

• The possibility of sequestering the greenhouse gas carbon dioxide in magnesite on a wide scale is being investigated. This research has focused on ophiolitic peridotites, where magnesite can be produced by enabling carbon dioxide to react with the rocks. In the case of ophiolites from Oman, some progress has been made. However, the main issue is that these artificial processes necessitate enough porosity permeability for the fluids to flow, which is rarely the case in peridotites.

• Magnesite is an excellent material for producing colourful, low-cost costume jewellery and art projects because of its low production costs and wide range of dyed colours. The disadvantage of using magnesite for jewellery is that it is less durable than other gem materials. Customers consider a material with a Mohs hardness of 3.5 to 5 in exchange for the low cost.

Magnesite Gemstones

Tumbled stones, beads, and cabochons are all made from magnesite. White magnesite has a porous structure. It can be cut and will absorb dye reliably to create almost any colour. Magnesite coloured in a turquoise colour has been used as a known and unknown turquoise replacement for nearly a century. Many people have been duped by magnesite dyed to resemble turquoise, while some have been duped into purchasing magnesite dyed to resemble lapis lazuli. When purchasing cabochons or tumbled stones with vibrant colours, be careful. Inquire whether they’ve been dyed. Scrubbing the substance with a cotton swab dipped in fingernail polish remover is a reasonably effective destructive test. Nail polish remover may be used to remove many of the dyes used on magnesite. Scratching the substance with a hardness pick or a nail may also reveal the bright white magnesite under the dyed surface.

Mineral Structure and Later Thermal Effects

The mineral properties of crystalline and cryptocrystalline magnesites are somewhat different. Cryptocrystalline magnesite is amorphous, consisting mainly of aggregates of fine grains, while crystalline magnesite has a well-developed crystal structure. Since clumped isotopic composition is determined by complex bonding, differences in the crystal structure are likely to influence how clumped isotopic signatures are recorded in these structures. As a result, later thermal events such as diagenesis/burial heating can alter their pristine signatures in different ways.

Properties of Magnesite

1. Magnesite in hand specimens can be difficult to classify since it often differs from its expected properties. Since it is frequently cryptocrystalline, its cleavage may be obscured. Magnesite is also silicified or mixed with chert, giving it a deceptively hard appearance. The apparent effervescence with HCl will be reduced if there is a significant chart present.

2. The measures outlined below will most likely assist you in identifying magnesite. Some people believe you have a sample suitable for destructive testing.

3. To check for an acid reaction, scrape the specimen over a streak plate and make some powder. Then, on the specimen, drop a drop of dilute (5%) hydrochloric acid and watch for an effervescent reaction. To see tiny bubbles emerging slowly from the powder, you need a hand lens.

4. To determine the specific gravity, do the following: The real gravity of magnesite is normally between 3.00 and 3.20. If there is a lot of quartz or chert in it, it may be as low as 2.8. If the specimen contains substantial chert or is silicified, the low specific gravity will be accompanied by a higher than average hardness.

5. If your specimen has a polished surface and you have a refractometer (and know how to use it), you will be able to perform one of the most accurate magnesite tests. Magnesite has a birefringence of 0.191 and a refractive index ranging from 1.509 to 1.700. The fact that it experiences birefringence blink in the 1.509 to 1.700 range is the most valuable property.

Conclusion

Magnesite is a mineral that is composed of magnesium carbonate (MgCO3) and belongs to the calcite group of carbonate minerals. It is a major source of magnesium. The mineral formed as a result of the action of magnesium-containing solutions on calcite or as an alteration product from magnesium-rich rocks. Radenthein, Austria; the Liaotung Peninsula, Liaoning Province, China; and Clark County, Nevada, United States are notable deposits. Iron is normally present, and between magnesite and siderite, a complete chemical substitution sequence occurs in which iron replaces magnesium. Magnesite uses are: it can be used as a refractory material, as a catalyst and filler in the manufacture of synthetic rubber, and as a raw material in the manufacture of magnesium chemicals and fertilizers.

The mid-latitude region is located roughly between 30 degrees and 60 degrees north or south of the equator. Steppe is usually a semi-arid area with rough grassland that receives less rainfall. Mid-latitude steppes lie in the outer regions of mid-latitude deserts. Unlike the desert, the mid-latitude steppe has little vegetation. The precipitation and humidity levels in regions of the mid-latitude steppe are extremely low. There is no or rare vegetation in mid-latitude deserts.

 

Synonyms of Steppe

Some of the popular synonyms of the steppe are pampas, savanna, pasture, meadow, etc.

 

What are Mid-Latitude Areas?

Mid-latitude areas are specific locations on the earth, situated particularly from 23°26’22 to 66°33’39 north and south of the equator.

 

Characteristics of Mid Latitude Steppe Climate

1. Usually, the mid-latitude steppe region in Asia, North America, and South America is found on the leeward side of the mountain range. A mountain range’s leeward side receives low precipitation, and this region also lacks moisture content in the air. These conditions create the ideal mid-latitude steppe climate. Low moisture and low rainfall are the primary characteristics of mid-latitude steppes.

2. The temperature in the mid-latitude steppe region depends on the elevation, latitude, and distance between land and water. As we go away from the equator, the temperature keeps on decreasing, whereas the temperature increases while moving towards the equator. In the case of elevation, the steppes found on higher elevations have a higher temperature, and steppes located on lower elevations will have a lower temperature.

3. The temperature usually falls between -40 degrees in winter to 40 degrees in the summer months.

4. As discussed earlier, the mid-latitude steppe is a semi-arid region which means that the amount of rainfall in this area is low, typically between 100 mm to 300 mm in a year.

5. Another vital thing to be noted is that if the mid-latitude steppe is closer to the tropical area, the humidity will influence the steppe’s climate. In that case, the duration of summer will be extended. Also, the presence of more humidity in the air will lead to more rainfall.

6. On the other hand, if the mid-latitude steppe region is near the coastal area, it will influence precipitation. The moisture-carrying wind from the sea will contribute to a more significant amount of rainfall in such a steppe. 

 

Example of Mid-Latitude Steppe

Some of the examples of mid-latitude steppe include- The Prairies in North America, Kansas in the US, the Great Steppe in Eastern Europe and Central Asia, the steppe in the eastern part of southern Andes.

 

What is a Mid-latitude Desert?

The mid-latitude desert is an excessively dry region with an arid climate located between 30 degrees and 60 degrees north and south of the equator. The placement of these deserts is found in the interior parts of the continents. The precipitation and humidity levels in these regions are extremely low. There is no or rare vegetation in mid-latitude deserts.

 

Characteristics of Mid-Latitude Desert Climate

1. A stark seasonal contrast in temperature can be observed in the mid-latitude deserts. In the hot summer of July, the temperature increases up to 20 degrees celsius and decreases to -27 degrees celsius in the harsh winter of January.

2. The summer temperature in mid-latitude deserts is not very hot due to its location in the temperate zone, which is cooler than the tropical zone. 

3. As these deserts are found in the inner regions of the continent far from the sea, they have low moisture content in the air. Therefore, the humidity level in these areas is significantly low as well.

4. Usually, mid-latitude deserts lie in the rain-shadow area of a mountain range that does not receive adequate rainfall.

5. The mid-latitude deserts are found in the temperate zone, which is relatively cooler than tropical and subtropical areas. Therefore, high atmospheric pressure and low moisture exist in these deserts, which are the main factors responsible for low precipitation.

6. Located in the far interior regions of the continents, these deserts are distant from water bodies and seas, which are the chief sources of moisture.

 

Examples of Mid-Latitude Desert

Some of the mid-latitude deserts that are found in the northern hemisphere include –

1. Gobi desert, Taklamakan desert, Greater Barsuki desert, Aral Karakum desert, Kyzylkum desert, Aralkum desert, and Ustyurt desert in Asia.

2. Great Basin desert and Mojave desert in North America. 

 

One of the notable examples of mid-latitude desert in the southern hemisphere is Patagonia in South America.

 

Difference Between Steppe And Desert Climates

A Desert climate holds less moisture in the air compared to the semi-arid steppe. The steppe region is usually covered with grass, whereas deserts are covered with sand and scattered cactus plants. Below are some of the main differences between steppes and deserts. 

• Deserts do not receive much rainfall as compared to steppes. 

• A desert is a home to some well-adapted and unusual plants whereas steppes have long grass and scrubs. 

• The steppe region is mostly covered with grass and scrubs while the desert region has sand and cactus plants scattered across the entire area. 

• Since steppes are semi-arid regions, they have fewer moisture deficits as compared to deserts.

 

Conclusion 

Now that you know the characteristics and meanings of mid-latitude steppes and desert climates, you can easily tell the difference between these regions. Make sure to go through the features and examples of both steppes and deserts to get a better understanding of these regions. 

One of the characteristics of mid-latitude steppes is that they are found in the Leeward Side of the mountain ranges in Asia, South America, and North America. On the other hand, deserts are found in the inner regions of the continent away from the sea. This is one of the major features that make mid-latitude steppes’ climate different from the desert climate. 

If you ever see ice sheets, you must have observed some peaks or rocks above the ice sheet which are higher in elevation than the surrounding ice. Different types of landforms can be seen on the surface of the Earth and it is also one of them. If we talk about an island, it is a mountain body that is exposed above and surrounded by the water. Similarly, Nunatak is a kind of glacial island that is exposed above and surrounded by ice. In this article, we will talk about Nunatak. We will learn nunatak’s meaning, its features, examples of nunatak glaciers in the world, etc. 

Nunatak Meaning

Nunatak is derived from the Inuit term “nunataq” which means lonely mountain in this American indigenous language. Nunatak is a rock or mountain that stands above the surrounding land of the ice sheet which is being glaciated. This kind of landform can be observed in the areas where a permanent ice sheet is there and nunataks are seen above the ice sheet. These are also known as “Glacial islands”.

Features

Some of the Features of the Nunatak Glacier are Given below:

• Some of the Nunataks are isolated mountains or rocks whereas some are found in clusters as well. For example, Queen Lousie Land, Greenland.

• They present reference points in ice caps or glaciers which can be identifiable.

• In ice sheets, these are the only regions where vegetation can be observed.

• Lifeforms here present unique habitats surrounded by ice sheets or glaciers.

• These generally are angular in shape along with rough & spiky points because of these features accumulation of ice on the tops are hampered ( although snow accumulation can happen on them ).

• It forms when the majority of the area is covered by the ice sheets or glacier which leaves the nunataks exposed above.

• The height of nunataks can be 20 feet or even more i.e. hundreds of feet. In Antarctica, the height of nunataks may be over 1000 feet. 

• They are found in the mountain regions where glaciers are there and these are found above the ice flows. They are also found where some former glacial activity has occurred in the mountain regions. Rocks & peaks with jagged surfaces can be found there along some of the areas below with smooth surfaces can also be found. 

Nunatak Definitions

Some of the Standard Definitions are Mentioned Below:

• “It is a hill or mountain completely surrounded by glacial ice.” – Merriam-Webster

• “It is a rock or a mountain that sticks up above the level of an area of ice or snow.” – Cambridge dictionary.

• “It is an isolated mountain peak projecting through the surface of surrounding glacial ice and supporting a distinct fauna and flora after the recession of the ice.” Or “a hill or mountain that has been completely encircled by a glacier.” Or “In Geology, it is an isolated mountain peak protruding through glacial ice.”  – Collins dictionary.

• “It is a rocky summit or mountain range that stands above a surrounding ice sheet in an area that is currently being glaciated.” – Oxford Reference.

Examples

• In Antarctica, some of the examples are Cook Nunataks, Andersson Nunatak, Lincoln Nunatak, Bergen Nunatak, Olander Nunatak, Bruna Nunatak, Bradley Nunatak, etc.

• In North America, some of the examples are Anoritooq Nunatak, Borgtinderne, C. H. Ostenfeld Nunatak, Crown Prince Frederick Range, Graah Mountains, Lille Renland, Peary Nunatak, Packsaddle Island, etc.

• In Eurasia, some of the examples are Lodalskåpa, Gora Severny Nunatak, Canisp, Stac Pollaidh, Suilven, etc.

Famous Nunataks

• Suilven is one of the famous Nunataks found in Scotland which looks like a mountain when we see it from land whereas it looks like a pillar when we see it from the sea. 

• Stac Pollaidh is also found in Scotland which is a mountain in the form of a ridge with smooth mountainsides that was carved out by glacial activity.

• Svarthamaren is one of the large Nunataks found in Antarctica which is famous because of home to one million birds i.e Antarctic Petrel during the breeding season.

Conclusion

Thus, to sum up, in the end, we can say that nunataks are a kind of landforms that can be found where glaciers are there and observed above the ice sheets. These are considered the only place where vegetation, as well as life, can be observed in the ice sheets. They form like an island in the ice sheets and where glacial activity has occurred earlier which leads to the formation of nunataks. These can rise from 20 feet to hundreds of feet and also over 100 feet as well. In this article, we learned about nunatak glacier, nunatak meaning and definitions, its features and examples, etc. This article will help you to understand new kinds of landforms found in the mountain/ glacier regions.

Ozone layer depletion is one of the most alarming environmental issues of the present time. The chloro- and Bromo- chemical compounds released into the atmosphere from industries and domestic buildings deplete the ozone layer. The most common compounds that cause ozone layer depletion are halocarbons like Chlorofluorocarbons. Chlorine reacts with atmospheric ozone, breaking an oxygen atom from the ozone ring and leads to a chain of reactions, in which the ozone gas is decomposed into oxygen and chlorine monoxide. Also, counteracting the ozone depletion in the stratosphere, ozone layer recovery has also been observed by scientists. 

The ozone layer depletion increased exponentially and the thinning of stratospheric ozone was observed more significantly in the polar regions, ever since researchers discovered the ozone hole. The gradual thinning of the ozone layer had led to the formation of an ozone hole over the Antarctic regions. Due to the depletion of the ozone layer, a greater amount of ultraviolet rays reaches the earth’s surface. There are several adverse effects of UV rays on humans as well as on the environment. Exposure to UV rays makes humans prone to cataracts, skin cancer, immune system damage, etc. However, recent climate surveys and research establish the fact that the ozone layer is recovering.

Ozone Cycle

The symbol of ozone gas is O3. It is formed when oxygen absorbs photons from the ultraviolet rays and photodissociation of oxygen molecules occurs. Here, the ozone cycle refers to the continuous process of dissociation and regeneration of ozone molecules due to the effect of ultraviolet radiations. On photodissociation, a diatomic oxygen molecule (O2) dissociates into two free radicals of atomic oxygen [O]. Each of these two atomic oxygen molecules reacts with diatomic oxygen molecules forming ozone gas. Therefore, every free radical of atomic oxygen forms one molecule of ozone gas, in reaction with diatomic oxygen.   

The chemical reactions involved in the formation of ozone are as follows.

O2 → [O] + [O]

[O] + O2 → O3

Ozone molecules split into diatomic oxygen and free radicals of atomic oxygen on the absorption of UV light. The resulting atomic oxygen radical again reacts with another diatomic oxygen molecule and forms an ozone molecule. This continuous process formation of ozone gas terminates when a free radical of atomic oxygen reacts with ozone and dissociates it into two molecules of diatomic oxygen. 

The chemical reactions involved in the splitting of ozone into two molecules of diatomic oxygen are as follows.

O3 + UV radiations → O2 + [O]

[O] + O3 → 2O2

The ozone layer depletion has occurred due to the reaction of ozone with highly reactive free radical catalysts like Bromine (Br ), Chlorine (Cl ), Nitrous oxide (NO ), and (OH ). Each of the above free radicals has an unpaired electron, that renders them highly reactive. The hydroxyl and nitric oxide free radicals occur naturally in the atmosphere whereas the free radicals of Chlorine and Bromine have human-made sources. The most common sources of the free radicals of chlorine and bromine are Chlorofluorocarbons (CFCs). These are mostly released from cooling appliances and certain industrial equipment. The CFCs are chemical compounds that travel as high as the stratosphere without decomposing or dissociating in the troposphere, as they exhibit low reactivity. 

On reaching the stratosphere, these chlorofluorocarbons absorb ultraviolet radiations and release the highly reactive free radicals of chlorine and bromine in the atmosphere.

The chemical reaction involved in the splitting of CFCs into free radicals of Chlorine and Bromine is as follows.

CFBr3 + Ultraviolet radiations → CFBr2 + Br

CFCl3 + Ultraviolet radiations → CFCl2 + Cl

These free radicals eventually react with the stratospheric ozone and degenerate it into diatomic oxygen through several types of catalytic reactions. For example, when the free radical of chlorine gas reacts with ozone, chlorine monoxide and diatomic oxygen are formed. The chlorine monoxide formed in the above step reacts with an ozone molecule and forms two molecules of diatomic oxygen. Now, another product of this reaction is a free radical of chlorine. Hence, a chain of reactions is initiated when a free radical of chlorine reacts with ozone. 

The chemical reactions involved in this chain reaction are as follows.

O3 + Cl → O2  + ClO 

O3 + ClO → 2O2 + Cl 

The free radical of chlorine produced in the above reaction will react with another ozone molecule forming diatomic oxygen and chlorine monoxide.

Ozone Hole Over the Antarctic 

The ozone column over the Antarctic regions had depleted by about 60 percent with respect to the average global ozone layer depletion. This phenomenon was recorded in 1985 by Joseph C. Farman, Jonathan D. Shanklin, and Brian G. Gardiner, in the British Antarctic Survey. In comparison with the previous records, this decrease in the ozone layer was found to be even greater than 50 percent. Ozone layer depletion is categorised into two phenomena, one is the depletion of ozone in the troposphere and the other is the formation of the ozone hole in the stratosphere at the polar regions.

Why is the Hole in the Ozone Layer Recovering?

The ozone hole recovery began in the late 1990s and the size of the hole has been decreasing ever since. In 1982, the size of the ozone hole was recorded to be 16.3 million km2. There are several international treaties such as NASA ozone layer recovery that are being religiously followed by various countries across the globe, to control the production and consumption of ozone-depleting substances. The recorded reductions are quite promising to anticipate that the ozone hole will be mostly recovered in the near future.

Ozone Layer Recovery

The ozone layer recovery has been one of the most significant agendas for the conservation of the environment. As per the recent records, the ozone layer is recovering and it is expected that the concentration of ozone in the atmosphere is likely to be restored like that of the 1970s by 2060s. The objective of the Montreal Protocol on Substances That Deplete The Ozone Layer was to control the production and use of CFCs and similar halocarbons that are potent threats to the ozone layer. Ideally, by 1998, the levels of global consumption of CFCs and similar halocarbons were to be reduced by 50 percent from the levels of 1986. By 2005, after several amendments, the consumption of CFCs and other ozone layer depleting substances was reduced by about 95 percent.

When is the Ozone Layer Expected to Recover?

It had been anticipated that the ozone holes over Antarctica will be of smaller sizes, if the consumption of CFCs and halocarbons is controlled, after 2040. Also, scientists have recorded that the stratospheric ozone levels will be restored to that of 1980, by 2060s. The concentration of ozone in the stratosphere and troposphere are affected by the levels of gases like carbon dioxide, nitrous oxide, methane, in the atmosphere. These gases can release reactive free radicals that deplete the ozone layer. The ozone level is expected to go up steadily but slowly since the halocarbons like CFCs stay longer in the atmosphere. 

An increase in stratospheric ozone levels was discovered in 2014 as a result of the phase-out of CFCs and other ozone-depleting substances across the globe. The practices as per the international treaties were to be accredited for this hike in the stratospheric ozone levels. Researchers observed that the ozone concentration in the upper stratosphere has been increasing since 2000, while the ozone hole over Antarctica has been reducing in size. The smallest ozone hole was recorded in 2019, this was a milestone in the ozone hole recovery and bolsters the fact that reduced consumption of substances that deplete ozone has the ozone recovered. This evidently shows how much has the ozone layer recovered with the international treaties to control the consumption of substances potent to deplete the ozone layer.

Ozone is one of the greenhouse gases and any changes in its concentration in the troposphere and stratosphere, have an impact on the earth’s temperature. The ozone hole over Antarctica is an opening for the harmful UV rays to be incident directly on its inhabitants. Also, the decrease in the concentration of stratospheric ozone has a cooling effect on the climate of our planet. Nevertheless, the increasing carbon dioxide levels in the atmosphere produces a counteractive heating effect as well. As the ozone layer is recovering gradually, researchers are anticipating that the ozone concentration in the stratosphere will be restored within a few decades. Hence, the earth ozone layer recovering will also reduce the cooling effect at the poles due to ozone depletion.