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World’s Physical Geography
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Discuss the supporting evidence as well as the counter arguments against Alfred Wegener's theory of continental drift.
It was in 1912 that the idea of continental drift gained a strong come-back, when Alfred Wegener propose for it; who supposed that landmasses were consolidated together all at once into big continent wholly called Pangaea and had since then driven separately. There are several solid grounds supportiRead more
It was in 1912 that the idea of continental drift gained a strong come-back, when Alfred Wegener propose for it; who supposed that landmasses were consolidated together all at once into big continent wholly called Pangaea and had since then driven separately. There are several solid grounds supporting this theory:
Grounds in Favor:
Among which are the Fit of Continents, meaning that if you ignore all other lines on your map and simply draw a line between their coastlines (the continental shelf), South America appears to fit perfectly in with Africa.
Fossil EvidenceSimilar fossil species were found on different continents which is an indication that these land masses once upon a time existed in close physical proximity, like the Mesosaurus.
The Geological Evidence: Rock formations or mountain ranges (like the Appalachian-Caledonian belt) that are similar between continents, indicating they share a common history Geologic feature -> Isostasy in Madagascar and Seychelles
Paleoclimate Evidence: The geological record contains rocks of glacial origin that are now distributed in essentially isolated localities across a number of continents, suggesting the existence at some time in the past of climates much more like those seen today than implied by barnacles.
Objections:
Mechanistic Explanation : A major criticism of Wegener’s theory was that there seemed to be no plausible mechanism by which continents could plow their way through the solid rock covering Earth nearly three miles deep.
Lack of Geological Processes: Some geologists claimed that the forces he suggested required to prod continents into motion were poorly understood (which was true) and Wegener’s theory lacked specific geological phenomena to explain how continental drift actually takes place.
Timing and Rate: Some of the issues raised by critics centered on the time and speed of continental drift as elucidated by Wegener where they noted that the movement of the continents was very fast and had not had a set time-frame.
Thus, one can state that Alfred Wegner offered a new magnificent theory of the continental drift which was based on the existence of geological, fossil and climatic evidence about the continental movement. Despite of its advantages like the match between continents and the related geological history, there were several objections concerning the absence of the reasonable mechanism and the detailed geological processes of the continental drift. These debates have since been followed by other debates that have facilitated new types of works and the coming up with of the theory of plate tectonics that explain the movement of Earth’s continent and oceanic plates.
See lessWhat is a climate tipping point, and why is it considered a critical concern in the context of climate change?
A climate tipping point refers to a critical threshold in the Earth's climate system. Crossing this threshold can lead to significant and often irreversible changes in the climate, ecosystem, or both. These changes can happen relatively quickly once the tipping point is passed, even if the initial dRead more
A climate tipping point refers to a critical threshold in the Earth’s climate system. Crossing this threshold can lead to significant and often irreversible changes in the climate, ecosystem, or both. These changes can happen relatively quickly once the tipping point is passed, even if the initial drivers pushing towards it are small or slow.
Climate tipping points are considered important because they can trigger cascading effects that amplify global warming and environmental disruption. For example, the melting of polar ice caps can accelerate as warmer temperatures reduce the reflective surface area (albedo effect), which in turn leads to more absorption of solar radiation and further warming. These feedback loops can create a domino effect that exacerbates climate change impacts beyond human control.
Understanding and identifying these tipping points is crucial for climate science and policy-making. It helps in setting more effective targets for greenhouse gas emissions reductions and conservation efforts to prevent or mitigate irreversible environmental changes.
See lessCritically assess the relationship between El Nino-Southern Oscillation (ENSO) events and the Indian monsoon.
The relationship between El Nino-Southern Oscillation (ENSO) events and the Indian monsoon is complex and significant, with both El Nino and La Nina phases having distinct impacts on the Indian monsoon rainfall (IMR). Here is a critical assessment of this relationship: El Nino Events: - Decreased IMRead more
The relationship between El Nino-Southern Oscillation (ENSO) events and the Indian monsoon is complex and significant, with both El Nino and La Nina phases having distinct impacts on the Indian monsoon rainfall (IMR). Here is a critical assessment of this relationship:
El Nino Events:
– Decreased IMR: El Nino events are associated with a decrease in IMR, leading to droughts and below-average rainfall.
– Changes in atmospheric circulation: El Nino events alter atmospheric circulation patterns, affecting moisture transport and rainfall distribution over India.
– Regional variability: While some regions in India may experience above-average rainfall during El Nino events, others may face drought-like conditions.
La Nina Events:
– Increased IMR: La Nina events are associated with an increase in IMR, leading to above-average rainfall and flooding in some regions.
– Enhanced monsoon activity: La Nina events strengthen the monsoon circulation, leading to more intense rainfall and a more active monsoon season.
– Benefits for agriculture: La Nina events are beneficial for India’s agriculture sector, which relies heavily on the monsoon rainfall.
Neutral Phase:
– Normal IMR: During the neutral phase of ENSO, IMR tends to be normal, with average rainfall and no significant deviations from the mean.
Impacts on Indian Monsoon:
– ENSO-induced variability: ENSO events can cause significant variability in IMR, leading to droughts or floods, which can have devastating impacts on agriculture, water resources, and food security.
– Regional disparities: The impacts of ENSO events on IMR can vary significantly across different regions in India, with some areas experiencing more severe effects than others.
– Predictability challenges: Predicting the exact impacts of ENSO events on IMR remains a challenge due to the complex interactions between atmospheric and oceanic processes.
In conclusion, ENSO events have a significant impact on the Indian monsoon, with both El Nino and La Nina phases having distinct effects on IMR. Understanding these relationships is crucial for predicting and preparing for extreme weather events, managing water resources, and ensuring food security in India.
See lessElaborate on the process of air mass formation while also providing a general classification of air masses.
Air mass formation occurs when a large body of air remains over a specific region for an extended period, taking on the characteristics of that region. This process involves: 1. Solar heating: The sun heats the Earth's surface, warming the air closest to the ground. 2. Expansion and rise: Warm air eRead more
Air mass formation occurs when a large body of air remains over a specific region for an extended period, taking on the characteristics of that region. This process involves:
1. Solar heating: The sun heats the Earth’s surface, warming the air closest to the ground.
2. Expansion and rise: Warm air expands and rises, creating an area of low pressure near the ground.
3. Replacement: Cooler air moves in to replace the risen air, creating a circulation pattern.
4. Cooling and sinking: As the air rises, it cools, eventually sinking back to the ground, creating a high-pressure system.
5. Homogenization: The air is mixed and homogenized, taking on the characteristics of the region.
Classification of air masses is based on their temperature and humidity properties, which are influenced by the region they form over. The main types of air masses are:
– Polar (P): Formed over polar regions, characterized by cold temperatures and low humidity.
– Tropical (T): Formed over tropical regions, characterized by warm temperatures and high humidity.
– Continental (c): Formed over land, characterized by low humidity and temperature extremes.
– Maritime (m): Formed over oceans, characterized by high humidity and moderate temperatures.
These air masses can be further classified as:
– Arctic (A): Extremely cold and dry, formed over Arctic regions.
– Antarctic (AA): Extremely cold and dry, formed over Antarctica.
– Equatorial (E): Very warm and humid, formed near the equator.
These classifications help understand the characteristics of air masses and their impact on weather patterns.
See lessAnalyze how plateaus impact both regional and global climate patterns.
Alteration of circulation patterns, precipitation patterns and temperatures, plateaus, which are flattened landforms raised notably higher than the surrounding land, have a substantive impact on climate on local, regional and even global contexts. At the regional scale, Plateaus are massive barriersRead more
Alteration of circulation patterns, precipitation patterns and temperatures, plateaus, which are flattened landforms raised notably higher than the surrounding land, have a substantive impact on climate on local, regional and even global contexts.
At the regional scale, Plateaus are massive barriers to the atmospheric flow disrupting weather greatly. For example, the tectonically formed Tibetan Plateau is the highest and the largest plateau in the world which significantly influences the Asian monsoon systems. It uplifts the tropical moist air from the Indian Ocean and makes it rise, cool and condense making the southern side have heavy rainfall and the northern side to be arid and referred to as the ‘rain shadow’ regions. This dynamic affects the regions’ water systems, distribution of agricultural land, and ecosystems.
Moreover, plateaus help in regulation of temperature at certain regions. It is a well-known fact that any higher ground will always be relatively colder as the altitude increases. One example is Deccan Plateau in India that have comparatively moderate climate to the lowlands and thus support diverse flora and fauna along with the different types of agriculture. Such temperature disparities can therefore trigger the formation of microclimates that has an impact on both the biological diversity as well as the numerous undertakings.
On a global level, there are key circulation systems that are affected by plateaus. The surface of the Tibetan Plateau gets warm in summer causing a formation of a high pressure system that can change the route of the jet stream hence modifying the weather in the Northern Hemisphere. Such changes may include shifts in storm routes, changes in precipitation areas, and other effects which are experienced as far as North America and Europe, which proves that plateaus significantly affect global climate.
Besides, it has been established that plateaus have an active function in the cycling of carbon on a global level. Alpine plateaus have specialized vegetation coming up due to the harsh environmental conditions and they sequester large amounts of carbon. But the human activities like deforestation and mining help in the emission of stored carbon into the atmosphere thus contributing to the global warming.
To sum up, plateaus bear a major impact on the regional and global climate as they determine circulation, precipitation, temperature regulation, and carbon storage. It is crucial to identify these impacts then as the information will help forecast and perhaps lessen the effects of climate change.
See lessWhat is the triple dip La Niña phenomenon? Discuss its likely impact on different regions of the world.
La Niña refers to the large-scale cooling of ocean surface temperatures in the central and eastern equatorial Pacific Ocean, coupled with changes in the tropical atmospheric circulation, namely winds, pressure and rainfall. The current La Niña episode started in September 2020 and has continued forRead more
La Niña refers to the large-scale cooling of ocean surface temperatures in the central and eastern equatorial Pacific Ocean, coupled with changes in the tropical atmospheric circulation, namely winds, pressure and rainfall. The current La Niña episode started in September 2020 and has continued for a third consecutive year and has thus been classified as a ‘triple dip’ La Niña. According to the World Meteorological Organization (WMO), the first “triple-dip” La Niña of the 21st century will continue to affect different parts of the world as given below:
In light of these impacts, concerns are raised about the unfolding humanitarian catastrophe for millions of people in different parts of the world especially in the Horn of Africa, which is witnessing one of the longest and the most severe droughts. It is necessary to provide tailored information to the humanitarian sector and to support sensitive sectors like agriculture, food security, health, and disaster risk reduction.
See lessHow does the theory of plate tectonics help in explaining the differences in the formation of the Himalayas and Andes mountains?
The Plate tectonics is a theory that explains the movement of the Earth's lithospheric plates and consequent formation of major landforms like mountains and events like volcanoes and earthquakes. The theory states that the Earth's lithosphere, which is the outermost layer of the planet, is broken inRead more
The Plate tectonics is a theory that explains the movement of the Earth’s lithospheric plates and consequent formation of major landforms like mountains and events like volcanoes and earthquakes. The theory states that the Earth’s lithosphere, which is the outermost layer of the planet, is broken into several large plates that move relative to each other.
The lithospheric plates rest on the underlying asthenosphere. These plates move due to the convection currents in the mantle, which are driven by the Earth’s internal heat sources, such as the radioactive decay of elements.
Formation of Himalayan Mountains:
Formation of Andes Mountains:
Therefore, there is a fundamental difference in the formation of Himalayas and Andes. While Himalayas are formed due to collision of two continental plates, the Andes are formed by the convergence of oceanic plate and continental plate (subduction of one plate under another). This subduction leads to formation of volcanoes in Andes such as Ojos Del Salado, Cotopaxi, Chimborazo etc., which are absent in the case of Himalayas.
See lessBring out the differences in the formation and role of ozone in the troposphere and stratosphere. Also, discuss the various strategies to reduce the impact of tropospheric ozone.
Ozone (03) is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in the Earth's upper atmosphere (stratosphere) and lower atmosphere oxygen (troposphere). Depending on where it is in the atmosphere, ozone affects life on Earth in either goodRead more
Ozone (03) is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in the Earth’s upper atmosphere (stratosphere) and lower atmosphere oxygen (troposphere). Depending on where it is in the atmosphere, ozone affects life on Earth in either good or bad ways. Formation of tropospheric and stratospheric ozone Tropospheric or ground-level ozone is formed primarily from photochemical reactions between two major classes of air pollutants, volatile organic compounds (VOCs) and nitrogen oxides (NOx). NOx and VOC break apart in the presence of intense sunlight and recombine into new structures, creating ozone. It is created by human activities as emissions from industrial facilities and electric utilities, motor vehicle exhaust, gasoline vapor, and chemical solvents are some of the major sources of NOx and VOC. On the other hand, stratospheric ozone is formed naturally through the interaction of solar ultraviolet (UV) radiation with molecular oxygen (02). Solar ultraviolet radiation breaks apart one oxygen molecule (02) to produce two oxygen atoms (20) and each of these highly reactive atoms combines with an oxygen molecule to produce an ozone molecule (03). These reactions occur continually whenever solar ultraviolet radiation is present in the stratosphere. Role of tropospheric and stratospheric ozone The tropospheric ozone or bad ozone can trigger a variety of health problems including chest pain, coughing, and throat irritation. It is also a major component of urban smog, which can worsen bronchitis and emphysema, trigger asthma, and permanently damage lung tissue. Further, bad ozone also damages vegetation and ecosystems as it leads to reduced agricultural crop and commercial forest yields, reduced growth and survivability of tree seedlings, and increased susceptibility to diseases, pests, and other stresses such as harsh weather. Whereas, the stratospheric ozone absorbs a portion of UV (Ultra Violet) light called UVB from the sun, preventing it from reaching the planet’s surface. Thus, it protects from many harmful effects, including skin cancers, cataracts, and harm to some crops and marine life. But this good ozone is gradually being destroyed by man-made chemicals referred to as ozone-depleting substances (ODS), including chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), etc.
Strategies to prevent the formation of tropospheric ozone.
The Government has further taken initiatives such as the National Clean Air Programme (NCAP), Graded Response Action Plan (GRAP), etc. to check ozone pollution and improve air quality. There is a need for the effective implementation of multi-faceted programs to cut NOx and VOC emissions from vehicles, industrial facilities, and electric utilities. Voluntary programs may also be started to encourage the communities to adopt practices, such as carpooling, to reduce harmful emissions.
See lessIt has been observed that the Greenland Ice Sheet (GrIS) is going through the biggest outright drop in its "surface mass" since record-keeping began in 1948. Examine the reasons behind this shrinkage and its possible consequences.
Antarctica and Greenland are home to Earth's only two ice sheets. It has been observed that the Greenland Ice Sheet (GrIS) is melting at a much faster pace than before. As per researchers, the GrIS has been losing mass for several decades due to both increased surface meltwater runoff and ablation oRead more
Antarctica and Greenland are home to Earth’s only two ice sheets. It has been observed that the Greenland Ice Sheet (GrIS) is melting at a much faster pace than before. As per researchers, the GrIS has been losing mass for several decades due to both increased surface meltwater runoff and ablation of marine-terminating outlet glaciers via calving and submarine melting, termed ice discharge.
Reasons for this shrinkage include:
The consequences of this phenomenon are:
How much and how quickly the Greenland Ice Sheet melts in the future will largely determine the ocean level rise in the future. If emissions continue to rise, the current rate of melting on the Greenland Ice Sheet is expected to double by the end of the century. Alarmingly, if all the ice on Greenland melted, it would raise global sea levels by 20 feet. Thus, adequate measures need to be taken in this regard.
See lessGive a brief account of various erosional and depositional landforms created by the movement of glaciers.
Answer: Masses of ice moving as sheets over the land or as linear flows down the slopes of mountains in broad trough-like valleys are called glaciers. They are formed through the processes of accumulation, compaction, and recrystallization of snow. The movement of a glacier is very slow and it movesRead more
Answer: Masses of ice moving as sheets over the land or as linear flows down the slopes of mountains in broad trough-like valleys are called glaciers. They are formed through the processes of accumulation, compaction, and recrystallization of snow. The movement of a glacier is very slow and it moves from a few centimeters to a few meters in a day. During this movement, a glacier forms various landforms. Erosional landforms created by the movement of a glacier are the following:
- Till deposits: The unassorted coarse and fine debris dropped by the melting glaciers is called glacial till. Most of the rock fragments in the till are angular to subangular in form.
- Outwash plains: Streams form by melting ice at the bottom, sides, or lower ends of glaciers. Some amount of rock debris small enough to be carried by such melt-water streams is washed down and deposited. Such glaciofluvial deposits are called outwash plains.
- Moraines: They are long ridges of deposits of glacial till. Based on their orientation with the glacier, they are termed terminal moraines, lateral moraines, horse-shoe-shaped ridge, ground moraines, and medial moraines.
- Eskers: These are sinuous ridges formed as a result of the melting of ice. During summers, the water accumulates beneath the glacier and flows like streams in a channel beneath the ice. This causes very coarse materials like boulders and blocks along with some minor fractions of rock debris carried into these streams and settle in the valley of ice beneath the glacier giving rise to eskers.
- Drumlins: Drumlins are smooth oval-shaped ridge-like features composed mainly of glacial till with some masses of gravel and sand.
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