CLIMATE Key Terms

Key Terms: CLIMATE

 

X.1. Atmosphere:

The atmosphere is a layer of gases that surrounds a celestial body such as a planet or a moon. In the case of Earth, the atmosphere is the layer of gases that envelop the planet, extending from the surface upward for hundreds of kilometers. It plays a vital role in supporting life and shaping Earth's climate and weather systems.

Example: Earth's atmosphere is primarily composed of nitrogen (about 78%) and oxygen (about 21%). Trace gases, including argon, carbon dioxide, neon, helium, and methane, make up the remaining small fraction of the atmosphere.

Atmospheric Gases: Atmospheric gases are the various gases that compose Earth's atmosphere. These gases play crucial roles in regulating the Earth's climate, supporting life, and maintaining atmospheric processes. The exact composition may vary slightly depending on factors such as location, altitude, and time, the following represents the approximate average composition of dry air at sea level: v  Nitrogen (N2): Nitrogen is the most abundant gas in Earth's atmosphere, constituting approximately 78.08% of its volume. v  Oxygen (O2): Oxygen is the second most abundant gas, making up about 20.95% of the atmosphere by volume. v  Argon (Ar): Argon is present in trace amounts, accounting for approximately 0.93% of atmospheric volume. v  Carbon Dioxide (CO2): Carbon dioxide is a minor component of the atmosphere, making up about 0.04% (400 parts per million) of its volume. However, its concentration has been increasing due to human activities such as burning fossil fuels and deforestation. v  Neon (Ne): Neon is present in trace amounts, constituting about 0.0018% of atmospheric volume. v  Helium (He): Helium is also found in trace amounts, making up approximately 0.0005% of atmospheric volume. v  Methane (CH4): Methane is present in trace amounts, accounting for about 0.0002% (2 parts per million) of atmospheric volume. v  Krypton (Kr): Krypton is present in very small amounts, making up approximately 0.0001% of atmospheric volume. v  Hydrogen (H2): Hydrogen is present in trace amounts, constituting about 0.00005% of atmospheric volume. v  Nitrous Oxide (N2O): Nitrous oxide is present in trace amounts, making up approximately 0.00003% of atmospheric volume.

 

X.2. Weather:

The term "weather" describes short-term conditions of the lower atmosphere, including temperature, humidity, wind direction, wind speed, and atmospheric pressure. It could be windy, stormy, snowing, sunny, cloudy, rainy, foggy, hot, or cold.

The elements of weather and climate are the same, i.e. temperature, atmospheric pressure, wind, humidity and precipitation.

Example: In Delhi, India, on a hot summer day in May, the weather typically exhibits high temperatures and dry conditions. The temperature may soar to around 40-45 degrees Celsius (104-113 degrees Fahrenheit), with clear skies and intense sunlight. The humidity levels are relatively low, typically ranging from 10% to 20%.

X.3. Climate:

Climate refers to the sum total of weather conditions and variations over a large area for a long period of time (more than thirty years).

Example: The climate of India can broadly be classified as a tropical monsoon one. The Indian Meteorological Department (IMD) designates four official seasons: Winter, from December to early April. Summer or pre-monsoon, from April to June (April to July in north-western India) Monsoon or rainy, from June to September.

X.4. Weather Vs Climate:

Sr.N.	Weather	Climate
1.	Weather is a specific event—like a rainstorm or hot day—that happens over a few hours, days, or weeks.	Climate is the average weather conditions in a place over 30 years or more.
2.	Rapid and frequent fluctuations.	Changes slowly and exhibits long-term trends
3.	It can be unpredictable.	It's predictable.
4.	Examples - sunny, rainy, cloudy, hot, cold, and stormy conditions, etc.	Examples - tropical, arid, savanna, Mediterranean, continental, and polar climates.

 

X.5. Koeppen Climatic Classification:

Koeppen identified a close relationship between the distribution of vegetation and climate. He selected certain values of temperature and precipitation and related them to the distribution of vegetation and used these values for classifying the climates. It is an empirical classification based on mean annual and mean monthly temperature and precipitation data.

Example: India's Köppen climate classification includes tropical rainforest (Af) in the Western Ghats, tropical savanna (Aw) in central India, tropical monsoon (Am) in the Indo-Gangetic plain, and subtropical (Cfa, Cwa) in northern India.

X.6. Monsoon:

The word monsoon is derived from the Arabic word 'mausim' which literally means season. • 'Monsoon' refers to the seasonal reversal in the wind direction during a year which is characterized by a pronounced shift in wind direction, often accompanied by significant changes in precipitation.

Example: Monsoons are most commonly associated with the Indian subcontinent but occur in various regions around the world, including Southeast Asia, East Asia, Africa, and North America.

Monsoon Break: A "monsoon break" refers to a temporary interruption or cessation of the typical monsoon rains. Monsoon breaks can occur during the rainy season when there is a period of several days to weeks with significantly reduced or no rainfall, amidst an otherwise wet season. These breaks are characterized by clear skies, decreased humidity, and often intense heat.

 

X.7. Retreat Monsoon:

The retreat of the monsoon in India refers to the seasonal withdrawal of the southwest monsoon winds from the Indian subcontinent. The retreat of the monsoon usually begins in September and continues through October. During this period, the southwest monsoon gradually weakens, and weather patterns shift. Rainfall becomes less frequent, and atmospheric conditions change as the monsoon winds retreat towards the Indian Ocean.

 

X.8. Seasons:

Wind is the natural movement of air in the Earth's atmosphere. It is caused by the uneven heating of the Earth's surface by the sun, which creates differences in air pressure. Air moves from areas of high pressure to areas of low pressure, which called as wind.

 Seasons are periods of the year characterized by distinct weather patterns and daylight hours resulting from the tilt of the Earth's axis relative to its orbit around the Sun.

Example: India experiences four primary seasons- Winter (December to February), Spring (March to May), Summer (June to September), Autumn (October to November).

 

X.9. Climate Change:

Climate change refers to long-term shifts in temperatures and weather patterns. Such shifts can be natural, due to changes in the sun’s activity or large volcanic eruptions. But since the 1800s, human activities have been the main driver of climate change, primarily due to the burning of fossil fuels like coal, oil and gas.

Example: The average temperature of the Earth’s surface is now about 1.1°C warmer than it was in the late 1800s (before the Industrial Revolution) and warmer than at any time in the last 100,000 years. The last decade (2011-2020) was the warmest on record, and each of the last four decades has been warmer than any previous decade since 1850.

X.10. Climate Crisis:

The climate crisis refers to the serious problems that are being caused, or are likely to be caused, by changes in the planet’s climate, including weather extremes and hazards, ocean acidification, and sea-level rise, loss of biodiversity, food and water insecurity, health risks, economic disruption, displacement, and even violent conflict.

Climate resilience is the capacity of a community or environment to anticipate and manage climate impacts, minimize their damage, and recover and transform as needed after the initial shock.

 Example: Since the 1800s, human activities have caused the Earth’s average temperature to increase by about 1.2° C – with more than two-thirds of this warming occurring since 1975. This is already causing significant damage to human societies and natural ecosystems in many parts of the world. More than 3 billion people live in places that are very vulnerable to the climate crisis, with lower income countries being disproportionately affected.

X.11. Climate Security:

Climate security refers to evaluating, managing, and reducing the risks to peace and stability brought on by the climate crisis. This means ensuring that climate mitigation and adaptation goes beyond doing no harm and contribute positively to peace and stability. It also means that conflict prevention and peacebuilding interventions take climate impacts into account. The technical solutions to climate action and adaptation can serve as opportunities to build peace and mend the social fabric, especially in countries affected by conflict and fragility.

 

Example: To access renewable energy can be a lifeline that supports clean water, light, warmth, and sustenance, as well as basic and emergency services. It also powers local economic development, while setting countries on a sustainable development pathway to recovery.

X.13. Net Zero:

Did you know? To keep global warming below 1.5°C, the world’s governments need to ensure that all greenhouse gas emissions peak by 2025, and reach net zero in the second half of this century. The IPCC has recommended to reduce CO2 emissions globally by 45% before 2030 (compared to 2010 levels) and reaching net zero by mid-century.

Net zero means cutting carbon emissions to a small amount of residual emissions that can be absorbed and durably stored by nature and other carbon dioxide removal measures, leaving zero in the atmosphere.

Example: India is committed to achieving the Net Zero emissions target by 2070.

 

 

X.14. Global Warming:

Global warming refers to the long-term increase in Earth's average surface temperature due to human activities that release greenhouse gases into the atmosphere. Some of the heat is trapped by gases such as carbon dioxide, methane, ozone, chlorofluorocarbon compounds (CFCs), and water vapour in the atmosphere. Thus, they add to the heating of the atmosphere. This causes global warming.

Example: One visible consequence of global warming is the melting of polar ice caps and glaciers. For instance, the Arctic region has experienced rapid ice loss, with Arctic sea ice declining at an alarming rate. This melting ice contributes to rising sea levels, posing threats to coastal communities, ecosystems, and infrastructure.

 

X.15. Greenhouse Gases (GHGs):

Greenhouse gases (GHGs) are gases in Earth's atmosphere that can trap heat, contributing to the greenhouse effect. These gases allow sunlight to enter the atmosphere freely, but they absorb and re-radiate infrared radiation (heat) emitted by the Earth's surface, trapping it within the atmosphere. This process leads to an increase in the Earth's surface temperature, creating a warmer climate.

Example: Greenhouse gases are carbon dioxide, methane, Nitrous Oxide, chlorofluorocarbon compounds (CFCs), and water vapour in the atmosphere.

 

X.16. Greenhouse Effect:

The greenhouse effect is the process through which heat is trapped near the Earth's surface by substances known as 'greenhouse gases.' This process makes Earth much warmer than it would be without an atmosphere. The greenhouse effect is one of the things that makes Earth a comfortable place to live.

Example: Greenhouse gases, such as carbon dioxide, methane, and water vapour, allow sunlight to enter the Earth's atmosphere but trap infrared radiation emitted by the Earth's surface. This trapped heat contributes to warming the lower atmosphere and the Earth's surface, creating the conditions necessary for life to thrive on the planet. However, human activities have enhanced the greenhouse effect by increasing the concentrations of greenhouse gases, leading to global warming and climate change.

 

X.17. Kyoto Protocol:

The Kyoto Protocol is an international treaty aimed at reducing greenhouse gas emissions and combating global warming. It was adopted in Kyoto, Japan, in December 1997, under the United Nations Framework Convention on Climate Change (UNFCCC). The protocol entered into force on February 16, 2005, and has been ratified by most countries around the world, including developed and developing nations.

v  The Kyoto Protocol establishes binding targets for developed countries, known as Annex I Parties, to reduce their greenhouse gas emissions by specified amounts below their 1990 levels. These targets vary for each country and are set for specific commitment periods.

 

Do You Know? Climate justice means putting equity and human rights at the core of decision-making and action on climate change. The concept has been widely used to refer to the unequal historical responsibility that countries and communities bear in relation to the climate crisis.

X.18. El Nino:

This is a name given to the periodic development of a warm ocean current along the coast of Peru as a temporary replacement of the cold Peruvian current. ‘El Nino’ is a Spanish word meaning ‘the child’, and refers to the baby Christ, as this current starts flowing during Christmas. The presence of the El Nino leads to an increase in sea-surface temperatures and weakening of the trade winds in the region. Its impact include increased cyclone activity, drought, and flooding.

Example: El Niño's usual impact in South Asia is to bring lesser than normal rainfall, which India noticed. There was a 36 percent deficit in August 2023 rainfall.

 

X.19. La Niña:

 La Niña means Little Girl in Spanish. La Niña has the opposite effect of El Niño. During La Niña events, trade winds are even stronger than usual, pushing more warm water toward Asia. Off the west coast of the Americas, upwelling increases, bringing cold, nutrient-rich water to the surface.

 Example: The study, by researchers at the Bengaluru-based National Institute of Advanced Studies and Pune-based Indian Institute of Tropical Meteorology, has argued that the unusual air quality in some Indian cities in the winter of 2022 could be attributed to the record-breaking spell of La Nina prevailing at that time.

 

X.20. Jet Stream:

These are a narrow belt of high altitude (above 12,000 m) westerly winds in the troposphere. Their speed varies from about 110 km/h in summer to about 184 km/h in winter. A number of separate jet streams have been identified. The most constant are the mid-latitude and the sub tropical jet stream.

Example: Subtropical Westerly Jet Streams- over India, these jet streams blow south of the Himalayas, all through the year except in summer. The western cyclonic disturbances experienced in the north and north-western parts of the country are brought in by this westerly flow. In summer, the subtropical westerly jet stream moves north of the Himalayas with the apparent movement of the sun. An easterly jet stream, called the sub-tropical easterly jet stream blows over peninsular India, approximately over 14°N during the summer months.

Western Cyclonic Disturbances The western cyclonic disturbances are weather phenomena of the winter months brought in by the westerly flow from the Mediterranean region. They usually influence the weather of the north and north-western regions of India. Tropical cyclones occur during the monsoon as well as in October - November, and are part of the easterly flow. These distrurbances affect the coastal regions of the country.

 

X.21. Polar Vortex:

The polar vortex is a large area of low-pressure and cold air that surrounds both of the Earth's poles. It forms and exists year-round but is strongest during the winter months when the temperature contrast between the polar regions and the mid-latitudes is greatest.

Example: The long and chilly winter in north India in 2019 could be linked to cold blasts from the Arctic region that have been spilling southwards since late December due to the breakdown of a wind circulation called the polar vortex.

X.22. Ozone Hole:

The ozone hole refers to a severe depletion of the ozone layer in Earth's stratosphere, particularly over the polar regions. It is characterized by a significant decrease in the concentration of ozone molecules (O3), which play a crucial role in absorbing harmful ultraviolet (UV) radiation from the Sun. The discovery of the ozone hole sparked global concern due to its potential impacts on human health, ecosystems, and the environment.

Example: The ozone hole in the Antarctic region refers to a severe depletion of the ozone layer that occurs over Antarctica during the Southern Hemisphere spring, particularly in September and October. It is characterized by a significant reduction in the concentration of ozone molecules (O3) in the stratosphere, leading to the formation of a large and persistent area of low ozone levels.

 

 

X.23. Stratosphere:

Region of the atmosphere between the troposphere and mesosphere, having a lower boundary of approximately 8 km at the poles to 15 km at the equator and an upper boundary of approximately 50 km. Depending upon latitude and season, the temperature in the lower stratosphere can increase, be isothermal, or even decrease with altitude, but the temperature in the upper stratosphere generally increases with height due to the absorption of UV radiation by ozone.

 

X.24. Montreal Protocol:

The Montreal Protocol on Substances that Deplete the Ozone Layer is an international treaty designed to protect the Earth's ozone layer by phasing out the production and consumption of ozone-depleting substances (ODS). It was adopted on September 16, 1987, in Montreal, Canada, and entered into force on January 1, 1989. The protocol is widely regarded as one of the most successful environmental treaties ever negotiated.

v  The Montreal Protocol targets a specific group of chemicals known as ozone-depleting substances (ODS), including chlorofluorocarbons (CFCs), halons, carbon tetrachloride, methyl chloroform, and hydrochlorofluorocarbons (HCFCs). These substances are commonly used in refrigeration, air conditioning, foam blowing, solvents, fire extinguishers, and other applications.

 

X.25. Carbon Footprint:

The term "carbon footprint" refers to the total amount of greenhouse gases, specifically carbon dioxide (CO2) and other greenhouse gases expressed as CO2 equivalents, emitted directly or indirectly by human activities. It quantifies the impact of an individual, organization, event, product, or service on climate change, typically measured in metric tons of CO2 equivalent per year.

Example: Carbon footprints are calculated by assessing the emissions associated with various activities across their entire lifecycle, including production, transportation, use, and disposal. These activities can include energy consumption (electricity and fuel usage), transportation (driving, flying, public transport), food production and consumption, waste generation, and other daily activities.

 

X.26. Ocean Acidification:

Ocean acidification refers to the ongoing decrease in the pH of Earth's oceans, primarily as a result of the absorption of excess carbon dioxide (CO2) from the atmosphere. When CO2 dissolves in seawater, it reacts with water to form carbonic acid, leading to a reduction in pH and an increase in the acidity of the ocean.

Example: Ocean acidification poses a serious threat to coral reef ecosystems and the myriad benefits they provide to society.

Doldrums: The equatorial region experiences direct sunlight year-round, causing warm air to rise and create low pressure. This belt, extending from the equator to 10°N and 10°S latitudes, lacks horizontal air movement, resulting in calm conditions known as the doldrums. These regions, also called the Inter-Tropical Convergence Zone (ITCZ), are areas of wind convergence due to airflow from subtropical high-pressure belts. Example: The doldrums can be seen in the maritime industry, particularly in sailing. Sailors navigating through the Atlantic Ocean near the equator may encounter the doldrums, which are characterized by calm or very light winds.

 

 

X.27. Insolation:

Insolation, short for "incoming solar radiation," refers to the solar energy that reaches the Earth's surface. Insolation plays a crucial role in driving Earth's climate, weather patterns, and various natural processes.

Example: Insolation plays a vital role in powering solar panels to generate electricity. Solar panels absorb sunlight and convert it into usable energy through photovoltaic cells, providing a clean and renewable source of electricity for homes, businesses, and other applications.

X.28. Albedo:

Albedo refers to the measure of how much sunlight is reflected off a surface, expressed as a percentage. It plays a crucial role in the Earth's energy balance and climate system. Surfaces with high albedo reflect more sunlight and absorb less heat, while surfaces with low albedo absorb more sunlight and retain more heat.

Example: Snow and ice have high albedo values, typically ranging from 50% to 90%. This means that they reflect a significant portion of incoming sunlight back into space. While, forests and vegetation generally have lower albedo values, ranging from 5% to 20%, as they absorb more sunlight and reflect less.

 

X.29. Inter-Tropical Convergence Zone (ITCZ):

The Inter-Tropical Convergence Zone (ITCZ) is a belt of low pressure near the equator where the trade winds from the Northern Hemisphere and Southern Hemisphere converge. It is characterized by rising air, convective activity, and abundant cloud formation, making it a region of frequent thunderstorms and precipitation.

Example: Sometimes describe the Inter-Tropical Convergence Zone, which reaches the Gangetic plain in July and lies between 20°N and 25°N latitudes, as the monsoon trough. This monsoon trough leads to the formation of thermal low over north and northwest regions in India.

Coriolis force: An apparent force caused by the earth’s rotation. The Coriolis force is responsible for deflecting winds towards the right in the northern hemisphere and towards the left in the southern hemisphere. This is also known as ‘Ferrel’s Law’.

 

X.30. Seasonal Wind:

Seasonal Wind The pattern of wind circulation is modified in different seasons due to the shifting of regions of maximum heating, pressure and wind belts.

Example: The most pronounced effect of seasonal wind shift is noticed in the monsoons, especially over southeast Asia.

 

X.31. Tropical Cyclones:

Tropical cyclones are violent storms that originate over oceans in tropical areas and move over to the coastal areas bringing about large-scale destruction caused by violent winds, very heavy rainfall and storm surges. This is one of the most devastating natural calamities.

Example: They are known as Cyclones/Chakrawat in the Indian Ocean, Hurricanes in the Atlantic, Typhoons in the Western Pacific and South China Sea, and Willy-willies in the Western Australia.

 

X.32. Extra-Tropical Cyclones:

The systems developing in the mid and high latitudes, beyond the tropics are called the middle latitudes or extratropical cyclones. The passage of the front causes abrupt changes in the weather conditions over the area in the middle and high latitudes.

Examples: Extratropical cyclones include blizzards, Nor'easters, and the ordinary low pressure systems that give the continents at mid-latitudes much of their precipitation.

X.33. Front:

In meteorology, a front refers to the boundary or transition zone between two air masses with contrasting properties, such as temperature, humidity, and density. Fronts are associated with changes in weather conditions, including changes in temperature, wind direction, and precipitation patterns. There are several types of fronts, each with distinct characteristics and weather effects.

Example: A cold front- Imagine a region where warm, humid air from the south is in place, while to the northwest, a colder air mass is advancing. As the cold air mass moves toward the warmer air mass, it acts as a boundary between the two air masses, creating a cold front.

 

X.34. Cryosphere:

One of the interrelated components of the Earth's system, the cryosphere is frozen water in the form of snow, permanently frozen ground (permafrost), floating ice, and glaciers. Fluctuations in the volume of the cryosphere cause changes in ocean sea level, which directly impact the atmosphere and biosphere.

Example: The continental ice sheets found in Greenland and Antarctica, as well as ice caps, glaciers, and areas of snow and permafrost.

X.35. Land-sea Breezes:

Land-sea breezes are local wind patterns caused by the temperature difference between land and sea surfaces. During the day, land heats up more quickly than water, creating low pressure over the land and high pressure over the sea. This temperature contrast causes a breeze to blow from the cooler sea towards the warmer land, known as the sea breeze. Conversely, at night, the land cools faster than the sea, reversing the pressure gradient and causing a breeze to blow from the land towards the sea, known as the land breeze. These daily wind patterns influence coastal climates and can have significant effects on local weather conditions.

X.36. Heat Island:

An urban area is characterized by temperatures higher than those of the surrounding non-urban area. As urban areas develop, buildings, roads, and other infrastructure replace open land and vegetation. These surfaces absorb more solar energy, which can create higher temperatures in urban areas.

Example: According to IIT Kharagpur research, From 2001 to 2017- the mean daytime temperature of surface urban heat island (UHI Intensity) went up to 2 degrees C for most cities like Delhi, Mumbai, Bengaluru, Hyderabad, and Chennai.

X.37. Paris Agreement:

The Paris Agreement is an international treaty adopted in December 2015 under the United Nations Framework Convention on Climate Change (UNFCCC). It represents a landmark agreement aimed at addressing climate change by reducing greenhouse gas emissions, enhancing climate resilience, and fostering sustainable development.

v  Long-term Goal: The central aim of the Paris Agreement is to limit global warming to well below 2 degrees Celsius (°C) above pre-industrial levels, while pursuing efforts to limit the temperature increase to 1.5°C. This ambitious goal acknowledges the urgency of addressing climate change and the need to avoid its most severe impacts.

 

X.38. Intergovernmental Panel on Climate Change (IPCC):

The Intergovernmental Panel on Climate Change (IPCC) is a scientific body established by the United Nations (UN) in 1988 to assess the scientific basis of climate change, its impacts, and the options for adaptation and mitigation. The IPCC provides policymakers with regular assessments of the state of climate science, based on the latest research findings from scientists around the world.

 

X.39. UNFCCC:

The United Nations Framework Convention on Climate Change (UNFCCC) is an international environmental treaty adopted in 1992 to combat dangerous human interference with the climate system. It entered into force in 1994 and enjoys near-universal membership, having been signed by 198 parties. It is the parent treaty of both the Paris Agreement and the Kyoto Protocol.

v  The UNFCCC facilitates intergovernmental climate change negotiations by organizing between two and four negotiating sessions each year, the largest and most important of which is the Conference of the Parties (COP). It also provides technical expertise assists in the analysis and review of climate change information and maintains the registry of Nationally Determined Contributions (NDC).

 

X.40. Nationally Determined Contributions (NDCs):

Nationally Determined Contributions (NDCs) are climate pledges and action plans that each country is required to develop in line with the Paris Agreement goal of limiting global warming to 1.5° C. NDCs represent short to medium-term plans that are updated every five years with higher ambition on climate.

v  NDCs outline mitigation and adaptation priorities a country will pursue to reduce greenhouse gas emissions, build resilience, and adapt to climate change, as well as financing strategies and monitoring and verification approaches. In 2023, the first in a series of global “stock takes” will conclude that assesses progress on the implementation of NDCs and Paris Agreement goals.

v  In August 2022, India updated its NDC according to which target to reduce emissions intensity of its GDP has been enhanced to 45 percent by 2030 from 2005 level, and the target on cumulative electric power installed capacity from non-fossil fuel-based energy resources has been enhanced to 50% by 2030.

 

UPSC Previous Year Questions   Q. The formation of ozone holes in the Antarctic region has been a cause of concern. What could be the reason for the formation of this hole? (2011) (a) Presence of prominent tropospheric turbulence; and inflow of chlorofluorocarbons (b) Presence of prominent polar front and stratospheric clouds; and inflow of chlorofluorocarbons (c) Absence of polar front and stratospheric clouds; and inflow of methane and chlorofluorocarbons (d) Increased temperature at polar region due to global warming   Q. The seasonal reversal of winds is the typical characteristic of (2014) (a) Equatorial climate (b) Mediterranean climate (c) Monsoon climate (d) All of the above climates

  

Ref- NCERT, UN, NASA, News Papers, UPSC…