Climate and Climate Change Module 4: Dynamics of Atmosphere Notes

GEOGRAPHY 177 - Climate and Climate Change Module 4: Dynamics of Atmosphere Notes

Introduction to Climate and Climate Change

  • Previous studies in atmospheric dynamics: Structure, composition, insolation, air pressure, winds, humidity, precipitation.

  • Importance of climatic elements on daily life: Housing, clothing, and food production.

  • Key topics to cover: Climate definitions, major climate regions, climate change causes and consequences, and global initiatives for climate change mitigation.

Outcomes of the Lesson

  • Differentiate between weather and climate.

  • Describe various climate regions.

  • Explain the concept of climatic change.

  • Identify causes and consequences of climate change.

  • Describe major global initiatives related to climate change.

9.1 WEATHER AND CLIMATE

A. Definitions

  • Atmosphere: The blanket of air surrounding Earth, constantly changing in temperature, pressure, wind, humidity, and precipitation.

  • Weather: The state of general atmospheric conditions with respect to temperature and pressure; changes daily and can be erratic. Meteorological agencies provide weather forecasts.

  • Climate: Long-term averaged weather conditions of a specific area, calculated over a period of 30 years according to the World Meteorological Organisation (WMO).

B. Difference between Weather and Climate (Table 9.1)

Criteria

Weather

Climate

Definition

Daily changes in atmospheric conditions

Averaged weather conditions of particular regions

Period of time

Short period - 24 hours

Long period - more than 30 years

Elements

Temperature, air pressure, wind, precipitation, humidity, sunshine, cloudiness

Average temperature, average pressure conditions, average wind velocity, etc

Areal Extent

Small area/Local

Large area/Global

Change

Very frequently

Largely permanent

Types

Different types of weather conditions prevail in a day

Broadly one type of climate is experienced in an area

C. Interconnected Atmospheric Elements

  • There is an inverse relationship among temperature, pressure, and wind:

    • High temperature typically results in low air pressure and vice versa.

  • These elements also influence precipitation, humidity, sunshine, and cloudiness.

9.2 FACTORS AFFECTING CLIMATE

A. Climatic Variation Factors

  1. Distance from the Equator (Latitude):

    • Equatorial regions are warmer due to direct sunlight; example: Maldives vs. Switzerland.

  2. Elevation:

    • Higher altitudes are cooler; the lapse rate is approximately 1°C decrease every 100 meters.

    • Example: Leh (higher altitude, cooler) vs. Jaisalmer.

  3. Global Winds and Ocean Currents:

    • Prevailing winds result from atmospheric circulation; bring moisture and influence precipitation.

    • Warm winds from sea are moisture-laden; cold winds from land are dry.

    • Coriolis Effect: Wind patterns are deflected due to Earth’s rotation.

  4. Geographic Character:

    • Influence of proximity to oceans and mountain directions on climate.

    • Windward regions (e.g., Mumbai) receive more rainfall compared to leeward counterparts (e.g., Nagpur).

  5. Vegetation:

    • Affects soil formation and temperature range; forests tend to have milder climates than deserts.

  6. Other Climate Controlling Factors (Table 9.2):

    • Land surface albedo, ocean evaporation, greenhouse gases, solar radiations, clouds, aerosols.

9.3 CLIMATIC REGIONS

A. Definition of Climate Regions

  • Climate regions are areas with homogeneous climatic characteristics and geographic continuity.

B. Historical Classification Attempts

  • Aristotle identified three thermal zones: Torrid, Temperate, and Frigid.

C. Koppen's Classification of Climate

  • Developed by Waldimir Koppen based on the relationship between climate and vegetation.

  • Five major climate regions based on temperature and precipitation: Tropical, Dry, Temperate, Cold, and Polar.

Design of Koppen's Classification

  • Major groups are denoted by capital letters (A, B, C, D, E) for temperature and B for precipitation.

  • Subgroups are indicated by lowercase letters, indicating seasonal characteristics of precipitation and temperature.

Major Climate Regions and Characteristics (Table 9.3)

Group A: Tropical Hot and Humid Climate

  • Af: Hot and rainy rainforest climate; humid all seasons.

  • Am: Tropical monsoon climate; seasonally excessive rainfall.

  • Aw: Tropical wet and dry climate; dry especially in winter.

Group B: Dry Climate

  • BWh: Hot desert climate (> 18°C).

  • BSh: Hot steppe climate (> 18°C).

  • BWk: Moderate latitude cold desert climate (< 18°C).

  • BSk: Moderate latitude cold steppe climate (< 18°C).

Group C: Warm Temperate Rainy Climate

  • Cf: Precipitation throughout the year (e.g., Cfa - humid subtropical, Cfb - marine west coast).

  • Cw: Mild winter and dry summers; includes subcategories (e.g., Cwa - subtropical monsoon).

  • Cs: Wet winters, dry summers; Mediterranean types (e.g., Csa, Csb).

Group D: Cold Snow Forest Climate

  • Average temperatures between 0°C to > 10°C.

  • Df: Humid cold climate with no dry season; includes various subcategories based on temperature variations (Dfa, Dfb, etc.).

  • Dw: Humid cold with dry winters; several sub-regions defined by summer warmth and winter dryness.

Group E: Polar Climate

  • Average temperature is <10°C.

  • ET: Tundra climate.

  • EF: Permanent snow field; ice cap conditions.

Geographic Distribution of Climate Regions

  • Regions divided into groups based on their climatic characteristics, as exemplified by maps and systemic representations.

9.3 CLIMATE CHANGE

A. Definition

  • Climate change refers to significant variations in the averaged weather conditions over time; a global phenomenon.

B. Understanding Climate Variability

  • Climate Variability: Anomalies in the existing state of climate observed over space and time; short-term changes.

  • Difference from Climate Change: Climate change indicates long-term trends or variations sustained over decades (Table 9.4).

C. Global Warming

  • Defined as the increase in the Earth's air temperature due to greenhouse gases, which absorb long-wave radiation.

  • Greenhouse Effect: The warming of the Earth's troposphere due to greenhouse gases preventing heat loss.

  • Major greenhouse gases: Carbon dioxide (CO₂), chlorofluorocarbons, methane, carbon monoxide, ozone, nitrous oxide.

  • Global temperature trends: Increased average temperature post-Industrial Revolution by over 1%, with predictions of continuing rise.

D. Climate Change Variability Statistics

  • Notable evidence includes 9 out of the 10 warmest years since 1880; specific years highlighted such as 1998 as the warmest.

9.4 CAUSES AND CONSEQUENCES OF CLIMATE CHANGE

A. Natural Causes

  1. Continental Drift: Altered positions of landmasses affecting climates.

  2. Ocean Currents: Massive heat transportation affecting climate patterns.

  3. Volcanoes: Eruptions release materials impacting temperature temporarily.

  4. Solar Output: Changes in the sun's intensity influence climate; example of the Little Ice Age.

  5. Earth's Orbital Changes: Milankovitch cycles modifying seasonal patterns.

B. Human-Induced Causes

  1. Fossil Fuels: Industrialization significantly increased greenhouse gas emissions.

  2. Land Use Change: Urbanization and deforestation altering climate conditions.

  3. Deforestation: Reduces carbon absorption capacity of forests.

  4. Agricultural Activities: Increased emissions of methane and carbon; notable impact from rice paddies and livestock.

C. Consequences of Climate Change

  • Impacts include melting glaciers, rising sea levels, extreme weather events, negative effects on agriculture, and implications for flora and fauna as well as human health.

  1. Melting of Glaciers and Ice Caps: Significant loss of glaciers observed since the 1960s.

  2. Rising Sea Levels: Increased acidification affecting marine life.

  3. Extreme Weather Events: Increased frequency of cyclones, droughts, and floods; case studies highlighted (e.g., Cyclone Tauktae).

  4. Impact on Agriculture: Climate sensitivity threatens food security; differing impacts across latitude.

  5. Flora and Fauna Disruption: Altered life cycles and migration patterns.

  6. Human Health Effects: Increased mortality from heat and respiratory issues; WHO estimates increased deaths due to climate change.

9.5 GLOBAL INITIATIVES ON CLIMATE CHANGE

A. Intergovernmental Panel on Climate Change (IPCC)

  • Created by UNEP and WMO in 1988; now has 195 member countries.

  • Main objective: Provide scientific information to help develop climate policies; produces assessments, synthesis, and methodology reports.

  • Divided into three working groups focusing on physical science, impacts, adaptation, and mitigation strategies.

B. Paris Climate Agreement

  • Adopted in 2015, effective from 2016; legally binding treaty for reducing greenhouse gas emissions and limiting global warming to < 2°C.

  • Replaces Kyoto Protocol considerations, requiring developed nations to give support to developing nations.

TERMINAL QUESTIONS

  1. Differentiate between weather and climate.

  2. Discuss the climate regions of the world.

  3. What are factors affecting the climate of a region?

  4. Define global warming and its importance.

  5. Describe climate change.

  6. Analyze the significance of the Paris Agreement.

  7. Define greenhouse and list greenhouse gases.

  8. Elaborate on factors propelling climate change.

  9. Describe the major effects of climate change.

  10. Discuss global initiatives for combating climate change.